Notice Decoder
Pick the notice code at the top of your IRS letter and its date. We explain it in your language and compute the real deadline — from template rules, never invented figures.
CP2000 — Proposed Changes to Your Return (Underreporter)
What this is
The IRS compared your return with income reported by employers, banks, and others, and found a mismatch. They propose changing your tax. This is a proposal — not a bill yet.
What happens if you ignore it
If you do not respond by the deadline, the IRS makes the change final and sends a Notice of Deficiency, then a bill — with the amount they chose, not yours.
Do this now
- Check each mismatched item against your own records (W-2s, 1099s).
- Agree, partially agree, or disagree on the response form — and sign it.
- If you sold stock or crypto, the issue is often missing cost basis, not missing income.
Not sure the letter is real?
Run it through the Scam Shield letter checker first — it compares the code against this library and the IRS's contact rules.