Additional tax from an examination (audit) has been assessed. Here is what it means, what usually happens next, and what to do.
On your account transcript it reads: 300 Additional tax or deficiency assessment by examination Adds to what you owe
TC 300 assesses additional tax resulting from an examination. It generally posts after you agreed to the proposed changes, did not respond to the examination letters, or the 90-day window on a notice of deficiency passed.
Reversal code: TC 301 — Tax abated by examination. When it posts after this code, the effect above is undone.
Also written as: IRS code 300, code 300 on transcript, 300 IRS code, transaction code 300.
A balance-due notice follows, with interest charged from the return's original due date and often a 20% accuracy-related penalty on the change. Collection then proceeds through the usual notice sequence unless you pay or arrange payment.
| On the same transcript | What it usually means |
|---|---|
| 420 → 300 → 421 | Examination closed with additional tax. |
| 300 with a penalty line | Accuracy-related penalty assessed with the examination change. |
| 300 → 301 later | Part of the assessment reduced, for example by audit reconsideration. |
If you missed the chance to disagree, audit reconsideration is available with new documentation.
Accuracy-related penalties can be removed with reasonable cause or other defenses.
An installment agreement prevents escalation toward levy.
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Decode my transcript →If the deadlines in your examination letters passed, you can request audit reconsideration with new information. If you hold a notice of deficiency and the 90 days have not passed, Tax Court is the route.
Interest on additional tax runs from the date the tax was originally due, not from the assessment date.
On your IRS account transcript for the tax year — in your IRS Online Account under tax records, or by mail using Form 4506-T. The transactions section lists each code with its description, date and amount. Return transcripts do not show transaction codes.
Yes. IRS code 300, code 300 on transcript, transaction code 300 and TC 300 all refer to the same three-digit transaction code the IRS posts to your account.