TC Codes Library

Every IRS account transcript is written in transaction codes — three-digit numbers that record what actually happened to an account, in the order it happened. The IRS Transcript Decoder looks up any single code instantly. This library goes further for the codes where a quick definition isn't enough — where the practitioner's next move depends on a closing code, a statute computation, or a distinction between two codes that look interchangeable but aren't.

Twenty-seven codes are live across two batches. Batch 1 covers the collection-resolution and statute cluster — Currently Not Collectible, Offers in Compromise, installment agreements, collection holds, statute waivers, and the fees and penalties that ride alongside them. Batch 2 adds the penalty cluster — refund freezes and the Failure to File, estimated tax, and Failure to Deposit penalties. More codes are planned; this library adds pages in batches rather than all at once, the same discipline the IRS Notice Library holds to.

Collection holds

Code	What it means
TC 470	A pending-claim hold on collection or notices — what it actually freezes depends entirely on its closing code.
TC 528	Ends a status 41/42 collection stay and returns the module to its prior posture.

Currently Not Collectible

Code	What it means
TC 531	Reverses a CNC determination and returns the account to active collection.
TC 534	Writes off one assessment whose collection statute expired inside a still-open module.
TC 537	The system-generated CNC reversal — a new liability appeared, not a reassessed hardship.

Fees and collection costs

Code	What it means
TC 360	Assesses lien filing fees or levy/sale costs — a charge that can survive the tax it was securing.
TC 361	Abates a lien or collection-cost fee — narrower than it sounds, and does not release the lien itself.

Offer in Compromise

Code	What it means
TC 481	OIC rejected — restarts the collection statute by pendency plus 30 days, and the assessment statute by pendency plus a full year.
TC 482	OIC withdrawn or terminated — the same one-year assessment-statute extension as a rejection, now confirmed.

Installment agreements

Code	What it means
TC 488	Deferred/installment status — the collection statute keeps running the whole time the agreement is in effect.
TC 489	Installment agreement defaulted — sends the module back through delinquent-account collection processing.

Statute

Code	What it means
TC 560	Extends the assessment statute by signed Form 872 — never the collection statute on tax already billed.
TC 860	Reinstates a balance abated by clerical error after the statute otherwise ran — narrow, and fact-dependent.

Exempt-organization penalty

Code	What it means
TC 234	Daily Delinquency Penalty on a late Form 990/5500 — a flat per-day charge First-Time Abate cannot reach.
TC 235	Abates the Daily Delinquency Penalty — reasonable cause is the only relief path available.

Refund freezes

Code	What it means
TC 130	Freezes an entire account from refunding over a liability the IRS says exists elsewhere — the indicator decides whose debt it actually is.
TC 131	Reverses a TC 130 refund freeze and lets the money flow — its sibling release code, TC 824, ends the same freeze by spending the credit instead.

Failure to File penalty

Code	What it means
TC 160	A Failure to File penalty an Audit or Collection employee computed and posted by hand, distinct from the identical penalty the system assesses on its own.
TC 161	Abates a Failure to File penalty already assessed — First-Time Abate, reasonable cause, and a correction of an invalid assessment all post under this same code.
TC 162	Not a dollar transaction — removes the restriction a manual TC 160 or 161 leaves behind so the system can compute the penalty on its own again.
TC 167	The computer’s own reversal of a computer-assessed Failure to File penalty when the return’s due date or tax due changes — a recalculation, not a relief grant.

Estimated tax penalty

Code	What it means
TC 170	Records an underpayment-of-estimated-tax penalty, self-assessed on Form 2210/2220 or manually assessed by the IRS — reasonable cause alone cannot remove it.
TC 171	Manually reduces or removes an estimated tax penalty — the penalty reason code behind it reveals exactly which narrow ground actually applied.
TC 176	Master File’s own automatic assessment of the estimated tax penalty — the fastest fix is usually correcting the payment data behind the number, not arguing relief.
TC 177	Master File’s automatic reversal of a TC 176 estimated tax penalty, triggered by the same payment corrections that created it — a systemic fix, not a relief grant.

Failure to Deposit penalty

Code	What it means
TC 180	Assesses the Failure to Deposit penalty on late or short employment/excise tax deposits — a tiered 2/5/10/15 percent rate structure, with First-Time Abate available by name.
TC 181	Removes a Failure to Deposit penalty in whole or in part — whether the route is a safe-harbor correction, First-Time Abate, or reasonable cause changes what actually gets filed.