ICD code T31.75 – Major burns affecting 70-79% of body surface

Key takeaways

T31.75 codes burns covering 70-79% of body surface, with third-degree burns over 50-59% of body surface. Both percentages must be documented explicitly.

The T31 category captures burn extent only. When the burn site is documented, pair it with a site-specific T20-T25 code to capture location and depth on the same claim.

T31.75 is complete at five characters; the A, D and S 7th characters belong to the site-specific T20-T25 codes, not to T31 extent codes.

Pabau’s claims management software connects to the Claim.MD clearinghouse for real-time eligibility checks, CMS-1500 claim submission, claim status tracking and ERA matching.

ICD-10 Code T31.75: Quick reference

ICD-10 Code T31.75 is the billable code for burns involving 70-79% of body surface, with third-degree burns covering 50-59% of body surface.

It is billable in the current ICD-10-CM code set. The table below gives the reference data coders check before assigning or crosswalking it, including chapter placement and the corrosion equivalent.

For how a diagnosis code travels from the chart to a paid claim, see our guide to what medical billing is.

What T31.75 covers: Code descriptor and clinical meaning

ICD-10 Code T31.75 captures the extent of a burn injury when two documented thresholds are met at once. Burns cover 70-79% of total body surface area (TBSA), and third-degree (full-thickness) burns cover 50-59% of body surface. Neither threshold alone is sufficient. A patient with 75% TBSA burns but third-degree burns over only 30% of body surface codes to T31.73, not T31.75.

T31 codes are extent-only codes. They tell a payer how much of the body surface is burned. They do not tell a payer where the burns are located or how deep the worst areas are in clinical terms. That information comes from the T20-T25 site-specific codes, which capture anatomical location and burn depth. In nearly all inpatient burn admissions, the coder submits a site-specific T-code alongside the T31 extent code.

The clinical context for T31.75 is severe. Burns covering 70-79% TBSA, with full-thickness burns over half the body, are among the highest-acuity injury categories in ICD-10-CM. Patients typically require intensive care, fluid resuscitation, and staged surgical debridement and grafting. Under the CMS ICD-10 coding guidelines, the T31 category records extent for tracking and reimbursement. Site-specific codes alone don’t carry that figure.

How T31.75 fits within the T31 category: The T31.7x subcategory grid

The T31.7x subcategory groups all burns with 70-79% TBSA involvement. The fifth character (the digit after the decimal) encodes the share of total body surface that is third-degree, in 10-point steps. Third-degree burns can’t exceed the total burned area, so the subcategory ends at T31.77. The chart below plots each fifth character against that 70-79% band.

Miscoding tends to happen at this step. Coders either omit the fifth character entirely or select the wrong value when documentation is ambiguous. The table adds a clinical note for each code in the band.

T32 is the parallel category for corrosion injuries caused by chemical agents. T32.75 is the corrosion equivalent of T31.75 and uses the same digit structure. Never assign T32 for a thermal burn. The two categories split on cause of injury, and severity plays no part in the choice.

Calculating TBSA and the third-degree percentage: Documentation standards

Two clinical measurement tools produce the TBSA and depth percentages coders need to assign T31.75. The physician must document both values explicitly.

• Rule of Nines: The standard adult TBSA estimation tool. Each major body region is assigned a multiple of 9%. Head and neck count for 9%, each arm 9%, each leg 18%, anterior trunk 18%, posterior trunk 18%, and perineum 1%. Total surface area burned is calculated by summing affected regions. This method is practical at the bedside and is recognized by the American Burn Association as appropriate for adults.
• Lund-Browder chart: A more precise tool that adjusts regional percentages for patient age. It is particularly useful for pediatric burn patients, whose head-to-leg proportions differ significantly from adults. Verified burn centers generally prefer it.
• Third-degree documentation: After calculating total TBSA, the physician must separately document what percentage of total body surface is full-thickness (third-degree). A note such as “third-degree burns estimated at 55% of body surface” supports T31.75. A share of the burned area alone (“half the burns are full-thickness”) is not enough, because the code measures against the whole body. Query the physician for the body-surface figure.
• Burn diagram or body map: Many burn centers document TBSA and depth using a body surface diagram in the chart. Coders should confirm this diagram matches the narrative physician note. If they conflict, query the physician before coding.

When documentation states total TBSA but does not specify the third-degree percentage, the coder cannot assign T31.75. T31.70 (0-9% third degree, the unspecified default) is the correct fallback, but it triggers a significant DRG downgrade. A documentation query to the attending physician before claim submission is almost always worth the turnaround time.

T31.75 vs. adjacent codes: Avoiding the most common mix-ups

Within the T31.7x band, every code differs only in the documented third-degree percentage. The table below shows the most commonly confused sibling codes alongside the corrosion equivalent. It also includes T31.70, the code most often assigned by default when documentation is insufficient.

ICD-10-CM instructional notes for the T31 category

The ICD-10-CM Tabular List carries one instructional note and one exclusion at the T31 category level. Both apply to every code in the series, including T31.75.

• Primary or supplementary use: “This category is to be used as the primary code only when the site of the burn is unspecified. It should be used as a supplementary code with categories T20-T25 when the site is specified.”
• Excludes1: Sunburn (L55.-).

Corrosions caused by chemical agents sit in their own category, T32. A chemical injury of this extent takes T32.75 rather than T31.75.

Inhalation injury carries no T31 note, but it is still coded when documented, following the Alphabetic Index. Smoke inhalation is T59.81-, with J70.5 for the resulting respiratory condition. Burns of the respiratory tract itself fall under T27.-.

ICD-10 burn code sequencing: When T31.75 is principal vs. secondary

The T31 category note sets the order. T31.75 is sequenced first only when the burn site is not specified. When sites are documented, T20-T25 codes lead and T31.75 supplements. In practice, that gives two scenarios.

• T31.75 as principal diagnosis: This applies only when the record does not specify the burn site. Diffuse burns across several documented sites don’t qualify, because each documented site gets its own T20-T25 code.
• T31.75 as secondary diagnosis (more common): A site-specific code from T20-T25 is sequenced first when the burn sites are documented. T31.75 is then added as an additional code to capture the total extent. The T31 code documents extent for severity and audit review.

MS-DRG mapping and reimbursement impact

T31.75 maps to the burn DRG family under the CMS MS-DRG system. DRG assignment depends on CC-level or MCC-level diagnoses (complications or comorbidities), skin graft procedures and, for MS-DRG 927, prolonged ventilation. Accurate coding decides which DRG fires. Undercoding, such as defaulting to T31.70 when T31.75 is warranted, can trigger a lower-weighted DRG with significantly reduced reimbursement.

CMS updates DRG groupings and relative weights each October. The table above reflects the general burn DRG family structure. Verify current DRG weights in the CMS ICD-10 coding and MS-DRG Definitions Manual for the applicable fiscal year. A documented CC or MCC moves a claim from MS-DRG 929 to MS-DRG 928, which is a meaningful reimbursement difference.

Tracking electronic remittance advice (ERAs) after adjudication shows which payers pay burn claims at a lower DRG than the one coded. That pattern can point back to secondary diagnoses missing from the claim.

Payer requirements and prior authorization for T31.75

Claims carrying T31.75 almost always involve inpatient acute care with high per-diem costs, which means payer scrutiny is elevated. The following requirements appear consistently across Medicare, Medicaid, and commercial payer policies. Local coverage determinations (LCDs) issued by Medicare Administrative Contractors (MACs) still vary by jurisdiction.

• Medical record documentation: The TBSA percentage and third-degree percentage must appear explicitly in physician-authored documentation, not only in nursing notes or burn diagrams. Many MAC LCDs require physician attestation of these values.
• Burn center verification: Payers with burn-specific LCDs may require that the admission occurred at an American Burn Association (ABA)-verified burn center. ABA verification does not guarantee payer acceptance, but absence of ABA status at a facility submitting T31.75 claims may trigger additional review.
• Fluid resuscitation records: Payers auditing large-TBSA burn claims often request fluid balance records to confirm the clinical severity is consistent with the coded extent. Parkland formula calculations and fluid resuscitation logs support the coded TBSA.
• Prior authorization: Many commercial payers require prior authorization for burn center admissions. Check the payer-specific policy before transfer or admission. Missing prior authorization on a T31.75 claim is one of the most common non-clinical denial triggers.

Why T31.75 claims get denied and how to prevent it

T31.75 denial patterns follow predictable causes. Most are preventable at the documentation and pre-submission review stage. The denial management workflow for major burn claims should flag each of the following before submission.

• No documented TBSA percentage: The physician note documents burns as “extensive” or “severe” without a numeric TBSA value. The coder cannot assign T31.75 without a documented figure in the 70-79% range. Prevention: CDI query before chart drop.
• Documented TBSA contradicts the coded percentage: The physician documents 65% TBSA but the coder assigns T31.75 (which requires 70-79% TBSA). Prevention: cross-reference the physician note and any burn diagrams before code selection.
• Fifth-character mismatch or absence: The third-degree percentage is absent, or stated only as a share of the burned area (“majority of burns are third degree”). The coder then defaults to T31.70 rather than querying. Prevention: query for third-degree burns as a percentage of total body surface.
• Missing inhalation injury code: The discharge summary documents smoke inhalation but the coder omits the inhalation codes (T59.81- with J70.5). Payer audits flag the missing complication code, and appeals follow. Prevention: include inhalation injury coding in every burn checklist.
• Site-specific T-code missing as principal: The claim carries T31.75 as the only burn code even though the record documents the burn sites. The payer’s claim editing system expects a T20-T25 code first when site information is available. Prevention: confirm both the site code and extent code are on the claim before submission.

Our reference to denial codes in billing lists the codes payers attach to burn claim rejections. Reviewing claim adjustment reason codes (CARCs) from ERA files after adjudication shows which denial pattern dominates a given payer mix.

Documentation checklist for coders assigning T31.75

This checklist captures the pre-submission verification steps that reduce T31.75 denials. Work through every item before the claim drops.

1. TBSA in range: Physician documentation explicitly states total TBSA burned is at or above 70% and below 80%. A value of exactly 70% qualifies; a value of 79% qualifies; 80% does not.
2. Third-degree percentage documented: Physician note or burn diagram states that third-degree (full-thickness) burns cover 50-59% of body surface. Vague language (“more than half are third degree”) requires a query before coding.
3. Burn diagram present: A body surface diagram or burn map is in the chart and consistent with the narrative note. If the diagram and the note conflict, query the physician before assigning the code.
4. Site-specific T-code present: When burn sites are documented, a code from T20-T25 is selected and sequenced first, identifying the site(s) of the most severe burns.
5. Inhalation injury coded if documented: If the record documents smoke inhalation or a respiratory tract burn, the claim carries the matching code.
6. Wound infection coded if documented: Any documented wound infection has an additional code assigned from the infection chapter.
7. Prior authorization confirmed: Authorization number for the burn center admission is on file before submission.

Our guide to submitting a clean claim covers the claim-level checks that apply to every diagnosis code category. Applying them to T31.75 claims cuts rework from the denials described above.

How claims management software supports T31.75 claims

A T31.75 claim carries two documented percentages, plus a site code and an extent code. Billing teams often still check eligibility and chase claim status by hand across payer portals, one burn claim at a time.

Pabau, the practice management platform we build, connects to the Claim.MD clearinghouse for professional claims. Its streamlined claims management runs real-time eligibility checks, submits CMS-1500 claims electronically, tracks claim status and matches ERAs to the claims they settle.

Once ERAs are matched, the team can see which burn claims came back short or denied, and which adjustment codes the payer used. That lets you fix the documentation pattern behind them instead of reworking claims one by one.

Streamline burn claim submissions with Pabau

Pabau connects to the Claim.MD clearinghouse for real-time eligibility checks, electronic CMS-1500 submission, claim status tracking and ERA matching. See how it helps your team catch claim problems before a payer does.

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Conclusion

T31.75 turns on two numbers, and the physician has to write both of them down. Build the CDI query into the burn workflow before the chart reaches coding, and ask for third-degree burns as a percentage of total body surface. That one query separates a T31.75 claim from a T31.70 downgrade.

The trade-off is turnaround time. A query holds the claim for a day or two, while a wrong fifth character can cost a lower-weighted DRG and an appeal. Book a demo to see how Pabau keeps eligibility checks, claim status and remittances in one place for your billing team.

Continue your research

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