Every IRS notice has a code in the corner, and that code tells you exactly where you stand and how much time you have. This library explains each notice in plain English: what it means, the deadline that matters, what happens if you ignore it, and what your options are. Find your letter below — the exact date printed on your copy controls every deadline.
By Sam Brotman, JD, LLM, MBA · Last updated August 2026
Letter 105-C: your refund claim was denied
The formal disallowance of a refund claim – including denied ERC claims. It starts a two-year deadline to sue under IRC § 6532. If your ERC was denied, here is what you can still do.
The collection ladder, in order
- CP14 — the first bill. Typically 21 days.
- CP501 — first reminder.
- CP503 — second reminder; enforcement is next.
- CP504 — intent to levy (state refund); 30 days.
- LT11 / Letter 1058 — FINAL notice; 30 days to request a Collection Due Process hearing before wage and bank levies.
- CP90 — final notice variant with the same CDP rights and 30-day clock.
- CP523 — installment agreement default; 30 days to cure.
Audit and matching notices
- CP2000 — proposed changes from a document mismatch; 30 days; frequently wrong.
- IRS audit letters — Letter 566, Letter 2205, and how to tell a real one from a scam.
The one rule that applies to every notice
The IRS runs on deadlines, and nearly every right you have — to a hearing, to an appeal, to Tax Court — expires on a printed date. Nothing dramatic happens the day a window closes; you simply lose options, and the later stages take more work to unwind. If you are not sure which notice you are holding or what it means, that is exactly what the free 15-minute call is for.
For the full collection process from first notice to resolution, see our IRS collections attorney page and The Complete Guide to IRS Collections.