Appendix D — Claim Form Field Reference: CMS-1500 and UB-04, Box by Box

Two forms, two vocabularies, one job. This appendix is the working reference for both: what goes in each field, who cares about it, and the specific way each one fails. Chapter 25 owns the CMS-1500 and Chapter 26 owns the UB-04; this is their combined index, plus a short translation note for the moment a payer stops naming boxes and starts naming loops.

Use it when a rejection or denial names a field. That is what it is for. A message reading "missing or invalid item 17b" or "Loop 2310A, NM109" is naming a place, and a biller who cannot translate the place has a vocabulary problem rather than a claim problem.

Almost nobody submits paper, and everybody still has to know the form, because the electronic claim is the same data in a different container and the item number is the industry's coordinate system (Chapter 25 §25.1). It will outlive the paper.

⚠️ Both forms are revised, and payers add requirements on top of them. The CMS-1500 version in force is printed on the form itself — the 02/12 version at the time of writing — and items have been repurposed between versions. The authoritative documents are the NUCC's reference instruction manual for the CMS-1500 and the NUBC's UB-04 Data Specifications Manual, plus each payer's companion guide. Verify before you rely on anything below.

D.1 The two forms, and the vocabulary that goes with each

The CMS-1500 describes services performed on a person. Everything it needs to say fits in a code, a modifier, a date, and a pointer.

The UB-04 describes an episode inside an institution, and an episode has properties a service does not: it started somewhere, it lasted a period, it was interrupted, it ended in a disposition, and it consumed benefit days. None of that is a procedure (Chapter 26 §26.6).

Why the paper CMS-1500 looks the way it does: it is designed to be scanned. The form is printed in red drop-out ink the scanner is calibrated not to see; nothing may be handwritten; nothing may fall outside its box or touch a printed line; and no highlighting, correction fluid, or staples may enter the data area. The rigid field positions and the six service lines are consequences of a scanner, not arbitrary bureaucracy (Chapter 25 §25.1).

D.2 The CMS-1500, item by item

Items 1–13 — who is the patient, who holds the coverage, is there other coverage

D.2a Items 9a–9d, and the block everyone leaves blank

Items 9, 9a, and 9d capture the OTHER coverage — the secondary policy, its holder, and the plan name. Three things follow from filling it in, and all three are the point: the primary payer learns other coverage exists · the secondary claim becomes possible (Chapter 28 §28.10 — a secondary claim generally needs the primary's remittance plus the secondary's identifying information) · and the patient's balance may not be theirs, which makes a bill to that patient a bill to the wrong party.

The block is blank on most claims and correctly blank on most claims, because most patients have one policy. The failure is not that it is usually empty. It is that nobody distinguishes "empty because there is none" from "empty because nobody asked" (Chapter 25 §25.2).

D.2b "Signature on file" is an assertion

Items 12 and 13 are commonly completed with the phrase rather than a signature, which is permitted when a signed authorization is actually on file and is current under the payer's rules. Chapter 25 §25.2 names it as a pattern: a form field that stands in for a document is an assertion about that document's existence — the same shape as GA, JW, and KX (Appendix B §B.11), in the oldest field on the form.

A practice that populates the phrase by default, across all patients, without a process that files anything, has automated a false statement — and has done it in the field that authorizes releasing the patient's medical information.

Items 14–23 — the circumstances

Note the asymmetry that trips everyone: TWELVE diagnoses on the claim, item 21 — but only FOUR pointers per line, item 24E. §D.3.

D.2c Item 22, and what a corrected claim actually is

Item 22 is small and it decides whether you are correcting a claim or creating a second one. It carries a resubmission code — 7 to replace, 8 to void — and the original claim's reference number (Chapter 29 §29.6).

Three failure modes:

• Resubmitting with item 22 blank creates a DUPLICATE, not a correction. The payer receives what looks like a second claim, denies it, and the original problem is still unfixed.
• The wrong original reference number attaches your correction to somebody else's claim.
• Voiding when you meant to replace withdraws the claim entirely — occasionally what you want and usually not.

You need the original claim number, and it comes back on the remittance (Chapter 28 §28.1). And correcting is not appealing: a corrected claim says here is different information; an appeal says your decision was wrong about the information you had. At some payers, submitting a corrected claim in place of an appeal forfeits the appeal rights attached to the original determination (Chapter 30 §30.1).

Item 24 — the service lines

   24A  DATE(S) OF SERVICE        from and to
   24B  PLACE OF SERVICE          the two-digit code — §D.2d
   24C  EMG                       emergency indicator, if the payer wants it
   24D  PROCEDURES, SERVICES,     the CPT/HCPCS code
        OR SUPPLIES               ► and up to FOUR MODIFIERS
   24E  DIAGNOSIS POINTER         the LETTERS from item 21 — §D.3
   24F  $ CHARGES                 the practice's charge
   24G  DAYS OR UNITS             ► the J-code arithmetic lands here
   24H  EPSDT / Family Plan
   24I  ID QUALIFIER              } the RENDERING provider — §D.4
   24J  RENDERING PROVIDER ID     }

The columns that cause the most trouble:

• 24D's modifier positions — there are four. A line needing more uses modifier 99, with the additional modifiers in item 19 (Chapter 14 §14.3, Chapter 25 §25.4).
• 24F is the CHARGE — not the allowed amount, not the expected payment. A charge below the allowed amount caps the payment (Chapter 23 §23.7).
• 24G is units, and Chapter 21's medically unlikely edits check this column.
• And each line has a SHADED upper portion carrying supplemental data with no item of its own: NDC information on drug lines (a qualifier, the 11-digit NDC, a unit-of-measure qualifier, and a quantity — and Chapter 20 §20.8 established that the NDC quantity and the 24G units are different numbers in different units of measure, correctly) · narratives for unlisted codes · supplemental provider identifiers · and anesthesia minutes where a payer wants them at the line level.

The shaded area is per line, and most billers never see it, because a chargemaster mapping populates it. Which means when it is wrong, it is wrong on every claim until somebody looks at the mapping (Chapter 25 §25.4).

D.2d Item 24B — place of service, per line

Two digits, entered per line — so a single claim can carry lines with different places of service, and that is correct when it happened. The codes this book uses (Chapter 23 §23.5, Chapter 25 §25.8):

Three field-level notes. It is per line, not per claim. It must be consistent with item 32 (§D.4). And the telehealth codes have moved — verify current policy rather than carry a habit.

Items 27–33 — assignment, totals, and the providers

D.3 Diagnosis pointers and the four-per-line rule

Item 21 holds up to twelve diagnoses, lettered A through L. Item 24E holds up to FOUR LETTERS per service line, indicating which of those diagnoses support that service (Chapter 25 §25.5).

Four rules.

1. Point letters, not numbers. The 02/12 version uses letters. Older habits produce numbers, and some systems display numbers while transmitting letters.
2. Point only what supports THAT line. A claim's twelve diagnoses do not all support every service. Pointing all four positions at everything is not thoroughness — it is a claim that the venipuncture was performed for the hypertension.
3. Sequence matters. The first pointer is the primary reason for that service.
4. A service pointed at a diagnosis that does not support it will deny — even when a supporting diagnosis is elsewhere on the claim (Chapter 22 §22.6).

A pointer is a claim about why a service was performed. If you would not say the sentence out loud, do not point the line.

D.4 The three provider identities

The NPI. A ten-digit identifier. Type 1 is an individual — a person, following them through their career. Type 2 is an organization. They are not interchangeable: the individual's Type 1 goes in the rendering field; the organization's Type 2 goes in the billing field. And an NPI proves identity and nothing else — not enrollment, not participation, not eligibility to be paid, which is exactly why Chapter 19 §19.5's referring-provider denial cannot be fixed by resubmitting.

Taxonomy carries the provider's specialty, and it matters more than most billers realize: Chapter 15 §15.2's new-versus-established test and Chapter 16 §16.2's initial-versus-subsequent test both turn on specialty as the payer has it recorded.

⚠️ Whose NPI goes in 24J on an incident-to claim carries the most money per keystroke on this form. Under the incident-to rule (Chapter 15 §15.11), a qualifying office service furnished by auxiliary personnel may be billed under the physician's NPI at 100% rather than the 85% that applies when a non-physician practitioner bills under their own. So the field decides the payment, and it decides it by naming a person.

The NPP's NPI on a qualifying claim is a silent underpayment. The physician's NPI on a non-qualifying claim is an overpayment asserting a supervision that did not occur. And the default — configuring the physician's NPI for all established patients and never re-evaluating — produces the second one every time a patient raises something new. The field is one entry and the rule requires a per-encounter judgment.

And one internal consistency check almost nobody runs (Chapter 25 §25.6):

   Does the place of service in 24B match the site in item 32?
   Does item 32's site match where the service was actually rendered?
   Is the billing provider in 33 the entity entitled to the payment?

All three can be individually plausible and jointly wrong, which is why the check has to compare them to each other rather than validate them separately. Chapter 23's Case Study 1 is exactly this: a practice converted to a hospital outpatient department with place of service still 11, paying at the office rate for a service performed in a facility. It never denied.

D.5 The fields that most often cause a rejection

A rejection is not a denial. A rejected claim was never adjudicated, has no appeal rights, and the timely filing clock never stopped (Chapter 27 §27.7, Chapter 29 §29.1).

   1.  PATIENT NOT FOUND ........... items 1a, 2, 3
       name, ID, or date of birth does not match the payer's record
       ► Chapter 24 §24.2 is the prevention

   2.  SUBSCRIBER / RELATIONSHIP ... items 4, 6, 11
       patient is not the subscriber and item 4 is blank

   3.  REFERRING PROVIDER ......... item 17b
       blank, wrong person, unenrolled, or name/NPI mismatch
       ► Chapter 19 §19.5

   4.  DIAGNOSIS PROBLEMS .......... item 21
       invalid code, wrong ICD indicator, or a code that
       requires more characters

   5.  POINTER PROBLEMS ............ item 24E
       pointing at a letter that has no diagnosis behind it

   6.  BILLING PROVIDER ............ items 33, 33a
       NPI/name mismatch, or an NPI not enrolled with the payer

   7.  MISSING REQUIRED FIELD ...... varies by payer
       ► the payer's companion guide says which

Six of the seven are front-end fields — Chapter 24's argument arriving as a rejection report. And cause seven is answered by the payer's COMPANION GUIDE: almost every payer of any size publishes one, usually in a provider portal, usually as a PDF nobody in the billing office has opened. The NUCC manual says what an item is FOR; the companion guide says what THIS payer requires in it, and where they differ for that payer's claims, the companion guide governs.

D.6 Account 10-4471's claim — the frozen canon

(Constructed teaching example, consistent with the Encounter file the book has built since Chapter 1.)

   1    Group Health Plan                    ► Northfield Mutual, commercial PPO
   1a   [insured's ID]                       ► from the card, not from memory
   2    [patient name]                       ► as it appears on the card
   3    [birth date] / F
   4    SAME                                 ► the patient IS the subscriber
   6    SELF
   9    [blank]                              ► no secondary coverage
   10a  NO   10b  NO   10c  NO               ► not employment, auto, or other accident
   11d  NO                                   ► no other health benefit plan
   12   SIGNATURE ON FILE                    ► and it is
   13   SIGNATURE ON FILE

   14   [blank or the onset qualifier]
   17   [BLANK]                              ► no referring provider
   19   [blank]
   20   NO                                   ► no outside lab charges on THIS claim
   21   ICD indicator: 0                     ► ICD-10-CM
        A  M25.561      B  E11.9
        C  I10          D  E78.5
   22   [blank]                              ► not a corrected claim
   23   [blank]                              ► no prior authorization required

   24  A: DOS      B: POS   D: CODE/MOD    E: PTR    F: CHARGE   G: UNITS
   ─────────────────────────────────────────────────────────────────────
   1   03/14–03/14   11     99214  25      A B C D    185.00       1
   2   03/14–03/14   11     20610  RT      A          150.00       1
   3   03/14–03/14   11     J1030            A         18.00       1
   4   03/14–03/14   11     36415            B         14.00       1
   ─────────────────────────────────────────────────────────────────────

   27   ACCEPT ASSIGNMENT?  YES              ► in network
   28   TOTAL CHARGE        $367.00
   29   AMOUNT PAID         $30.00           ► the copay collected at check-in
   32   [blank]                              ► service performed at the billing address
   33   Northgate Family Medicine
   33a  [Type 2 NPI]                         ► the ORGANIZATION
   24J  [Type 1 NPI]                         ► the PHYSICIAN who performed it

Four fields on this claim are worth memorizing, because each one is a rule in miniature.

The pointers: A B C D · A · A · B. Line 1 uses all four because the E/M genuinely addressed four problems — which is Chapter 15's problems element and Chapter 14 §14.4's modifier 25 evidence appearing as a claim field. Line 4 points at B, not A, because the blood was drawn for the hemoglobin A1c. Pointing it at the knee would assert that a venipuncture treats knee pain. And nothing points at D alone, because the lipid panel is on the reference laboratory's claim (Chapter 19 §19.12).

Item 17 is blank, and that is correct. The physician who performed the service is the patient's own primary care physician; nobody referred her. A biller who populated item 17 with the performing physician would have created §D.5's third rejection cause out of nothing.

Item 20 is "no." The reference laboratory bills 83036 and 80061 on its own claim. Northgate did not purchase those tests and does not report them here.

Item 29 is \$30.00. The copay collected at check-in goes here, and a claim that omits it asks the payer to pay an amount the practice has already partly collected. Chapter 28 §28.5 covers what the remittance does with it, and Chapter 28 §28.11 shows the patient-side twin: a statement that does not show the credit asks the patient for money they already handed over.

Three things are absent from this claim, correctly, and each was decided by a chapter: the lidocaine (Chapter 17 §17.1's surgical package, Chapter 20 §20.10's usual supplies, Chapter 21 §21.6's standards of practice — three independent reasons, one absent line) · 83036 and 80061 (Chapter 19 §19.12) · and 99000, specimen handling, which Northgate has never asked whether it could bill.

D.7 The UB-04, in blocks

The UB-04 has 81 form locators. Learning them as a list is hopeless; learning them as six blocks is manageable (Chapter 26 §26.2).

   FL 1–13      WHO AND WHERE
                the provider, the patient, the control number,
                THE TYPE OF BILL (FL 4), the STATEMENT COVERS
                PERIOD (FL 6), and patient demographics

   FL 14–41     THE CIRCUMSTANCES
                admission date/hour/type/source (14–17),
                DISCHARGE STATUS (17),
                CONDITION CODES (18–28),
                OCCURRENCE CODES (31–34),
                OCCURRENCE SPAN CODES (35–36),
                VALUE CODES (39–41)

   FL 42–49     THE CHARGES
                REVENUE CODE (42) · description (43) ·
                HCPCS/rate (44) · service date (45) ·
                units (46) · total charges (47) ·
                non-covered charges (48)

   FL 50–65     THE PAYERS
                payer name, health plan ID, prior payments,
                estimated amount due, the insured, and
                TREATMENT AUTHORIZATION CODES (63)

   FL 66–75     THE DIAGNOSES AND PROCEDURES
                ICD indicator (66), PRINCIPAL and other
                DIAGNOSES with POA indicators (67),
                ADMITTING DIAGNOSIS (69), reason for visit (70),
                PRINCIPAL and other PROCEDURES (74)

   FL 76–81     THE PROVIDERS AND THE REST
                attending (76), operating (77), other (78–79),
                remarks (80), code-code field (81)

Three navigational facts. FL 4 and FL 6 do more work than any other pair on the form. FL 42–49 is the only block that repeats — twenty-two lines per page, multiple pages, with FL 47's total on the final page and revenue code 0001 as the total line. And the diagnosis block is where inpatient payment is actually determined, which is the single largest difference from the CMS-1500: FL 67's principal diagnosis and its secondary diagnoses, with their POA indicators, drive the DRG (Chapter 33).

D.8 The UB-04 by form locator

⚠️ This table lists the form locators this book teaches, not all eighty-one. The UB-04 Data Specifications Manual is the authority on every field and on what each one accepts — and unlike the NUCC's free manual, it is a subscription publication, which is worth knowing before you go looking for it.

D.8a FL 3a versus FL 3b — the field that makes autoposting work

FL 3a is the PATIENT CONTROL NUMBER: the facility's own identifier for this claim or account. The payer returns it on the remittance, which is how the payment gets posted to the right account (Chapter 28 §28.5).

FL 3b is the MEDICAL RECORD NUMBER: the facility's identifier for this patient, across all their encounters.

One is per encounter. One is per person. A patient with eleven admissions has eleven patient control numbers and one medical record number.

Why it matters: a facility that populates the medical record number into FL 3a gets remittances it cannot post automatically, because the returned identifier does not identify an account. Chapter 28 §28.7's autoposting depends on FL 3a coming back — this is one of the very few fields on the form whose sole purpose is to make the money land in the right place.

And if the same value appears on every one of that patient's claims, none of them will autopost.

D.9 Type of bill, digit by digit

FL 4, and it is the most information-dense field on either claim form. It is read as a sequence, each position answering a different question, and it is commonly written as three digits with a leading zero — so a "131" appears as 0131.

   0  1  3  1
   │  │  │  └── FREQUENCY — what kind of submission is this?
   │  │  └───── BILL CLASSIFICATION — what kind of care?
   │  └──────── FACILITY TYPE — what kind of facility?
   └─────────── leading zero

Facility type — the first meaningful digit:

Bill classification — the second. For hospitals (facility type 1):

Frequency — the third, and the one that causes damage:

0131 = hospital · outpatient · admit through discharge.

That is the emergency department anchor's facility claim, Account 22-9107's, and the type of bill on Chapter 26 §26.9's reconstruction. Read it as three answers rather than as a number and it stops being arbitrary. 0111 — hospital · inpatient Part A · admit through discharge — is the inpatient equivalent, and 831 is the ambulatory surgery center's (Chapter 34 §34.9).

Two things the frequency digit decides. 7 versus 8: a replacement submits a corrected claim that supersedes the original; a void withdraws it entirely. This is the institutional twin of item 22's resubmission code, and the failure is identical: submitting a corrected claim with frequency 1 creates a duplicate, not a correction. And 2/3/4 are a sequence — interim billing on a long stay produces a first, some number of continuing, and a last claim, submitted in order and not overlapping.

Both errors produce the same thing: A DUPLICATE.

D.10 Revenue codes and the HCPCS pairing

A REVENUE CODE SAYS WHERE. A HCPCS CODE SAYS WHAT (Chapter 26 §26.4).

A revenue code is a four-digit code identifying the department or cost center that provided the service or item. Every charge line on a UB-04 has one, which is the structural difference from the CMS-1500, where a line has a procedure code and nothing about department.

Three rules. Revenue codes are grouped by hundreds and the hundreds are meaningful: 02xx is largely ancillary supply and pharmacy, 03xx laboratory and radiology, 04xx therapy and emergency, 06xx specialized drugs and services, 07xx diagnostic services. 0001 is the total line and appears once, on the last page. And the 011x–021x range encodes something no professional claim carries — the ACCOMMODATION (private, semi-private, ward) and the LEVEL OF CARE (general medical/surgical, intensive care, coronary care, nursery). A stay that moves between units produces lines under more than one code, with units showing days at each level. A private room the patient requested where semi-private was medically sufficient is generally a non-covered differential, which lands in FL 48.

The room and board lines are also the fastest sanity check on a facility claim. Add the units across the accommodation lines: they should reconcile to the statement-covers period, allowing for the discharge-day convention. When they do not, something about the dates or the transfers is wrong.

The pairing rule:

   INPATIENT (TOB x1x)                            (Chapter 26 §26.5)
     ► revenue codes required
     ► HCPCS generally NOT required on most lines
       (the DRG is derived from diagnoses and procedures
        in FL 67 and FL 74 — Chapter 33)

   OUTPATIENT (TOB x3x)
     ► revenue codes required
     ► HCPCS REQUIRED on most lines
       (payment is per service under OPPS — Chapter 34)

Some revenue codes always require a HCPCS — 0636 is the standing example. Some are never paired with one — room and board, most obviously. And a payer's requirements can be stricter than the general rule; the companion guide is the document.

The revenue code follows the DEPARTMENT that performed the service, not the department the patient arrived in. A radiograph on an emergency department patient goes under 0320, diagnostic radiology — not 0450.

⚠️ Where facility drug billing dies: revenue code 0636. It requires a HCPCS code and units on the same line — it is the revenue code that says this is a specific drug in a specific quantity. The units are Chapter 20 §20.3's arithmetic, the NDC is Chapter 20 §20.8's problem arriving in the supplemental data, and the waste question is Chapter 20 §20.4's. A facility billing drugs under 0250 when 0636 is required reports the charge without the identifying detail, and the line pays as an undifferentiated pharmacy charge — or does not pay at all.

And the pairing lives in the chargemaster (Chapter 23 §23.8) — tens of thousands of lines, each carrying a description, a charge, a revenue code, and where required a HCPCS code. A facility coder who receives a denial for a revenue-code/HCPCS mismatch is looking at a chargemaster problem wearing a claim's clothes (Chapter 26 §26.5, and Chapter 29 §29.4 gives it a root-cause category).

D.11 Condition, occurrence, occurrence span, and value codes

Four families, and they are distinguished by SHAPE rather than by subject matter.

   IS IT TRUE?          → CONDITION       (a fact)         FL 18–28
   WHEN DID IT HAPPEN?  → OCCURRENCE      (a date)         FL 31–34
   HOW LONG?            → OCCURRENCE SPAN (a range)        FL 35–36
   HOW MUCH / HOW MANY? → VALUE           (an amount)      FL 39–41

The two condition codes this book uses:

These fields drive payment more often than students expect. A value code reporting covered days, an occurrence span reporting a qualifying stay, a condition code reporting a readmission — each one can change what a claim pays without touching a single procedure code.

And they are populated by different people. Registration supplies admission source and type; the unit supplies discharge status; utilization review supplies condition code 44; the business office supplies value codes for benefit amounts. A facility claim is assembled from four departments' contributions, which is why §D.14's reading order does not start with the codes.

D.12 Patient discharge status and the transfer rule

FL 17, two digits, and it decides more money than any other small field on the form. It reports where the patient went at the end of the stay.

The field has sixty-odd possible values; these are the ones that recur (Chapter 26 §26.7). Read the current NUBC list before assigning one you have not used.

The transfer rule. Under Medicare's inpatient prospective payment system, a hospital that TRANSFERS a patient rather than discharging them may be paid a per-diem amount rather than the full DRG — under defined circumstances, for defined DRGs, when the length of stay is below the geometric mean. Chapter 33 §33.8 covers the arithmetic.

A discharge status of 01 on a stay that was actually a transfer overstates the payment, and a transfer status on an actual discharge understates it. Both are wrong on a claim that is otherwise perfect, and neither denies.

Two more reasons the field matters. Readmission programs use it — a patient discharged home who returns within a defined window counts differently from one transferred. And 07, left against medical advice, is clinically and legally significant in ways that have nothing to do with billing. It is a fact about what happened, and coding it because the patient was not formally discharged misreports a clinical event.

Three patterns a reviewer looks for: a status of 01 where the record documents a transfer — the overpayment direction · a status of 30 on a claim that is not an interim claim, which is a mismatch between FL 17 and FL 4's frequency digit, and the two fields have to agree · and a facility whose distribution of discharge statuses differs markedly from comparable facilities, which is measurable from claims data with no chart at all.

The mechanism, stated plainly: discharge status is frequently entered by unit clerical staff at the end of a stay, from a discharge order, under time pressure, into a field with sixty-odd values. It is not a coding decision and it is not usually reviewed by anyone who codes. The remedy is to reconcile FL 17 against the discharge summary, on a sample, on a schedule.

D.13 FL 63 and FL 80 — the two fields that carry words

FL 63, treatment authorization codes, is Chapter 24 §24.6's authorization number on the institutional claim — and Chapter 24's warning applies unchanged: the number without its scope is a number, not a record, and the scope does not fit in the field.

FL 80, remarks, is a free-text field.

FL 80 is the field where the truth frequently sits. Chapter 26 §26.10's worked example turns on exactly this: a remark saying the patient was transferred, on a claim whose FL 17 says discharged home.

Somebody wrote down what happened in the one field nobody adjudicates, and reading it is the cheapest review step on the form.

The specific pattern to look for is a remark in FL 80 contradicting a coded field. It costs nothing to check and it is the only place on the claim where a human being explained themselves.

D.14 Reading a UB-04 you did not create

   READING A UB-04 — IN THIS ORDER              (Chapter 26 §26.10)

   1. FL 4  TYPE OF BILL
            What kind of claim is this, and is the FREQUENCY right?
            ► a corrected claim with frequency 1 is a duplicate

   2. FL 6  STATEMENT COVERS PERIOD
            Do all the service dates fall inside it?
            ► and on an interim claim, does it overlap the last one?

   3. FL 17 DISCHARGE STATUS
            Does it match the record? Does it match FL 4's frequency?
            ► 30 "still a patient" on a non-interim claim is a mismatch

   4. FL 42 REVENUE CODES
            Is 0636 used where a drug needs detail?
            Is there a HCPCS where the setting requires one?

   5. FL 67 DIAGNOSES
            Is the principal diagnosis the reason for the encounter?
            Are the POA indicators present? (Ch. 33 §33.7)

   6. THE CODES
            Last. They are usually fine.

Three things are wrong more often than the codes: the type of bill's frequency digit · the discharge status, entered by someone who is not a coder · and a revenue code that does not match the charge.

This is the same lesson Chapter 25's 📋 teaches on the professional side, and it is the most transferable skill in either chapter: the instinct is to check the codes, and the codes are usually fine. On a denied claim of either kind, work the non-clinical fields first.

D.15 From item number to loop and segment

A rejection message naming an ITEM is describing the form. A rejection naming a LOOP or SEGMENT is describing the 837. They are the same problem in two vocabularies, and a biller needs both. Chapter 27 §27.4 is the section that teaches the translation, and its three-word vocabulary is the whole of it:

A LOOP is a level. "Loop 2400" means "at the service-line level." A SEGMENT is a line of data inside a loop, identified by a two- or three-character tag. A DATA ELEMENT is one field inside a segment, referred to by position.

Three things to carry out of that table.

The four modifier positions are SV101-3 through SV101-6 — so the four-modifier limit is in the transaction, not on the paper, which is why modifier 99 exists (Chapter 14 §14.3).

The pointers are letters on the form and numbers in the transaction. Item 24E uses A B C D; the 837 uses 1:2:3:4, referring to positions in the HI segment. They are the same claim, and a biller who learned pointers as letters should recognize them as numbers.

And two limits the paper imposes that the transaction does not. The six service lines belong to the form — an 837P is not limited to six, and a claim split at six is frequently an artifact of software designed against the paper. When a system says a claim must be split, ask whether that is the payer's rule or the software's (Chapter 27 §27.3).

The institutional differences are structural (Chapter 27 §27.3): the 837I carries revenue codes and the 837P does not · the 837I carries the condition, occurrence, occurrence span, and value families, which have no professional counterpart · and the 837P carries diagnosis pointers per service line, while the institutional claim links diagnoses to the claim rather than to each line — which is why Chapter 26 has no pointer discussion at all.