IRS NOTICE REFERENCE
Understanding your CP21A notice
We sent you this notice because we made the changes to your tax return. You owe because of the changes.
General information only. Not legal or tax advice.
Notice details
- Notice code
- CP21A
- Category
- Balance due and collection
- Severity tier
- Tier 2 — Action or response expected. The IRS has taken or proposed an action and expects a response or payment.
- Governing law
- §6303; §6321 (Internal Revenue Code sections)
- Source
- IRS.gov — Understanding Your IRS Notice
What this notice is
We sent you this notice because we made the changes to your tax return. You owe because of the changes.
Source: IRS.gov. Reproduced for reference. General information — not legal or tax advice.
What the IRS says to do
If you agree with the changes we made, pay the amount you owe by the date printed on your notice . Pay online now to ensure timely receipt of your payment. If you’re unable to pay the full amount you owe, explore alternative payment options like a payment plan, temporary collection delay, or an offer in compromise. Be sure to correct your copy of your tax return for your records. If you disagree with the changes we made , contact us at the number provided on your notice.
This is the IRS’s own guidance reproduced from the IRS notice page. It describes the IRS’s process — it is not legal or tax advice from TaxRiskOS.
Governing IRS procedure (Internal Revenue Manual)
The IRS’s own internal procedures for handling this notice type are documented in the Internal Revenue Manual:
- IRM 5.19.1 — 5.19.1 Balance Due
- IRM 5.19.4 — 5.19.4 Enforcement Action
- IRM 5.1.1 — 5.1.1 Miscellaneous Collection Procedures
Reference to published IRS procedure. General information — not legal or tax advice.
Official IRS reference
Read the official notice page on IRS.gov: https://www.irs.gov/individuals/understanding-your-cp21a-notice
Related tools
TaxRiskOS is workflow software for practitioners — it captures the notice, computes the deadline, surfaces the escalation tier, and builds a document checklist. It documents process; it does not give advice or draft responses.
Check this notice’s deadline (free tool)