Every IRS account is a ledger of transaction codes, and those codes answer the questions taxpayers pay good money to have answered: when was the tax assessed, what penalties are on the account, is collection paused, has the file gone to exam. Pull your account transcripts and you are holding the IRS's own case notes. Here is the decoder.
The Assessment Codes
TC 150 is the big one: the return posted and the tax was assessed. The date next to it starts the 10-year collection clock for that assessment. TC 290 and TC 300 are additional assessments - 290 from adjustments, 300 from an examination - and each starts its own collection clock. A year with a 150 and a later 300 is running two statutes at once, which is exactly the kind of detail that changes strategy.
The Penalty and Interest Codes
TC 166 and 160 are failure-to-file penalties, TC 276 and 270 are failure-to-pay, TC 196 is assessed interest. Seeing how much of a balance is penalty rather than tax tells you instantly how much abatement is worth pursuing. A transcript heavy with 166 and 276 entries is a transcript with money in it.
The Status Codes That Reveal Strategy
TC 530 means the account went into currently not collectible status - and the closing code next to it often shows the income level that will reactivate it. TC 480 means an offer in compromise is pending, which also means the collection statute is paused. TC 520 is a collection hold: bankruptcy, litigation, or a collection due process hearing depending on its closing code, all of which freeze the clock. TC 550 means the collection deadline was extended - worth scrutinizing, because extensions have rules. TC 582 means a federal tax lien is on file.
On the examination side, TC 420 means the return was selected for audit, and TC 922 means the underreporter unit matched a 1099 or W-2 you did not report and a CP2000 is coming or already came.
Why This Is the First Document I Pull
Every case I take starts with transcripts, because every strategic question - statute timing, penalty exposure, compliance gaps, what the IRS has actually done versus what its letters threaten - is answered there in writing. You can request your own through IRS online services, or a power of attorney lets me pull every year at once. If you want yours read by someone who has read thousands, that is a short conversation. Let's talk.