ICD code T31.87 – Burns involving 80-89% body surface with 70-79% third degree burns

Key takeaways

T31.87 is the billable ICD-10-CM code for burns covering 80-89% of body surface, with 70-79% third degree.

Both figures are shares of the whole body, never shares of the burned area alone.

T31 codes report extent rather than location, so a T20-T29 site code is always sequenced first.

The chart has to carry total TBSA and third degree TBSA as two separate numbers.

Practice management software like Pabau builds the claim from the invoice, checks eligibility, and tracks it to payment.

What ICD-10 code T31.87 covers, and when you can bill it

ICD-10 code T31.87 reports burns across 80-89% of body surface, where 70-79% of that body surface is third degree. It is billable and specific, so it stands on its own line of a claim. What it does not tell the payer is where on the body the burn sits. That job belongs to a T20-T29 site code, and T31.87 is sequenced behind it.

T31.87 has been in the ICD-10-CM code set since the United States adopted it on October 1, 2015. It has come through every annual update since, and it remains valid for the FY2026 year. Even so, re-check it each October 1, because that is when new revisions take effect.

Where T31.87 sits on the T31.8x ladder

Every code in the T31.8x group covers the same total extent, which is 80-89% of body surface burned. Only the last digit moves. It records how much of the body surface carries full thickness injury, in bands of ten percentage points.

Laid out side by side, the group reads as a ladder. Each rung lifts the third degree band by ten points, and T31.87 sits second from the top.

Notice where the ladder ends. Third degree burns are part of the total burned surface, so the third degree figure can never climb above the total. A group capped at 89% cannot carry a rung for 90% or more. That makes T31.88 the last child code, and T31.89 does not exist.

The other T31 subcategories work the same way across the rest of the ICD-10 diagnostic codes library, from T31.0 upward. Learn the pattern once and every burn extent code in the chapter becomes readable.

Why the third degree figure is measured against the whole body

Third degree burns destroy the epidermis and the dermis, then reach into the subcutaneous tissue. They do not blanch under pressure. They are often painless at the burn site itself, because the nerve endings there have been destroyed.

The second figure in the code is the one people misread. The 70-79% in T31.87 is a share of the whole body, not a share of the burned area. Picture a patient with 85% of body surface burned, and 72% of body surface full thickness. That patient codes to T31.87.

Now change one number. If only 60% of body surface is full thickness within the same 85% burn, the claim codes to T31.86 instead. Read that 60% as a share of the burned area and you land on the wrong rung entirely.

How to measure TBSA before you reach for a T31 code

Every T31 code rests on a TBSA estimate, and that estimate has to come from the chart rather than the coder. Two tools are accepted, and the patient’s age decides which one applies.

Rule of Nines (adults)

The Rule of Nines splits the adult body into regions worth 9% each, or simple multiples of 9%. Burn diagrams drawn from it are quick to read. Confirm which tool produced the diagram before you trust the percentages on it.

Lund-Browder chart (children)

The Lund-Browder chart adjusts those regions for age. A two-year-old’s head is roughly 17% of body surface, against 9% in an adult. Run the Rule of Nines on that child and the estimate comes out low, which walks the claim down to the wrong sibling code. The record should name the tool that was used.

What the record needs before T31.87 will hold up

An auditor reading the chart should be able to rebuild the code from it, without calling anyone. Six items do that work.

• Total TBSA percentage. A numeric figure, with the estimation method named alongside it.
• Third degree TBSA percentage. Recorded separately, as a share of the whole body. A figure inside the 70-79% band is what supports T31.87.
• Burn depth by zone. Each burned area classified as first degree, second degree (superficial or deep partial), or third degree.
• Cause of the burn. Flame, scald, chemical, electrical, or radiation. This is what the external cause code is built from.
• Every site burned. Needed to assign the companion T20-T29 site codes that sit ahead of T31.87.
• Patient age. This decides whether the Rule of Nines or the Lund-Browder chart applies.

Burn diagrams help, as long as each zone is labeled with its own percentage. A shaded outline with no numbers on it gives a coder no figure to work from.

T31.87 vs T31.88: One digit, two different claims

These two codes share a total extent of 80-89%. The third degree band is the only thing separating them, and it moves by ten points. T31.87 needs 70-79%, while T31.88 needs 80-89%.

Both errors come from the same root, which is a chart that describes the burn in words instead of numbers. When a physician writes “third degree burns over most of the burned surface”, neither code can be assigned. Send a query before the claim goes out, not after the denial comes back.

How a T31.87 claim moves, and where it stalls

A severe burn admission produces one of the longest claims a practice will ever send. Once you can see the order it comes together in, the failure points are easy to spot.

1. The burn team records total TBSA and third degree TBSA at admission, naming the assessment tool.
2. The coder assigns a T20-T29 site code for each region burned, each with its seventh character.
3. T31.87 goes on next, reporting extent for the patient as a whole.
4. External cause, activity and status codes follow, drawn from the admission history.
5. The claim is transmitted, and the remittance comes back with either a payment or a denial code.

Before you submit: A five-point check

Run this over the claim while it is still editable. Each line takes a few seconds and each one maps to a denial reason.

• Is a T20-T29 site code sequenced ahead of T31.87?
• Does the chart state a third degree percentage inside the 70-79% band?
• Is that percentage written as a share of the whole body?
• Do the site codes carry a seventh character, and does T31.87 correctly carry none?
• Is there an external cause code explaining how the burn happened?

The mistakes that come back as denials

• T31.87 sequenced first. Under ICD-10-CM Official Guidelines Section I.C.19, a T31 code is not the principal diagnosis once the site is documented. Lead with the site code instead.
• One site code for a multi-region burn. Each region burned needs its own T20-T29 code. T31.87 covers total extent, not any single area.
• Extent confused with location. T20-T29 says where the burn is. T31.87 says how much of the patient it covers. Both belong on the claim.
• A seventh character bolted onto T31.87. Site codes take A, D or S. T31 codes take none at all.
• Downcoding to dodge a query. A missing third degree percentage is a question for the physician. Dropping to a lower sibling code is not a safe harbor on audit.

When a burn claim does come back rejected, a documented denial management process decides whether it gets reworked quickly or quietly written off. High-acuity claims are worth too much to leave sitting in a queue.

The codes that ride along with T31.87

T31.87 never travels alone. A severe burn claim carries a site code, this extent code, and a short run of external cause codes explaining how the injury happened.

Chemical injuries sit outside this pattern. A corrosion is reported with T54 for the corrosive substance and X46 for accidental contact, rather than an X00-X19 fire code. Extent for a corrosion comes from category T32, not T31.

Assembling a claim this long by hand invites transcription slips. Good claims management software pulls the line items straight off the patient’s invoice, so what leaves the practice matches what was charged.

How Pabau keeps a long burn claim moving

Most burn billing teams work across two screens. The chart lives in one system, the claim is keyed into another, and the percentages get retyped somewhere in between. Every retype is a chance to drop a digit.

Practice management software like Pabau closes that loop. Pabau builds the claim directly from the invoice on the patient record, so the codes your team assigned are the codes that go out. Coverage is checked in real time before the encounter, which surfaces eligibility problems while you can still act on them.

After submission, Pabau tracks the status of each claim and posts the electronic remittance advice back against the invoice. Your biller can see what paid and what did not, without logging into a separate payer portal. That is less chasing, and a shorter path from discharge to payment.

Build burn claims straight from the patient record

Pabau generates claims from your invoices, checks eligibility in real time, and tracks every submission through to remittance. See how that fits a high-acuity burn billing workflow.

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Conclusion

T31.87 comes down to two numbers, both measured against the whole body. Get them written into the chart at admission and the code picks itself.

So the work that protects this claim happens before coding starts. A physician who records total TBSA and third degree TBSA separately saves the biller a query, a delay, and often a denial. One number on its own leaves the coder with a question to send back.

If your burn claims still get keyed in twice, the problem is the workflow rather than the coding. Book a demo to see how Pabau builds the claim from the patient record and follows it through to payment.

Continue your research

Need to understand burn claim denials in depth? Denial management in healthcare covers how to build a systematic response workflow for high-acuity claim rejections.

Submitting clean claims for complex diagnoses? Clean claim requirements explains what payers look for before processing a multi-code submission like T31.87 plus T20-T29.

Looking for a US medical billing clearinghouse? Medical claims clearinghouse options breaks down how electronic claim validation works and what to look for in a clearinghouse partner.

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