IRS Notice CP21B: Adjusted Return — Balance Due

What does an IRS CP21B notice mean?

A CP21B confirms the IRS made changes to your tax account — often from an amended return or a requested adjustment — and the result is a balance due. The notice details the adjustment and the amount owed, including any penalties and interest.

Why did you receive a CP21B?

An amendment or correction to your return increased your tax liability, or an adjustment you requested had the side effect of creating a balance.

How to respond to a CP21B notice

If the change is correct, pay the balance by the due date or set up an installment agreement to avoid additional penalties. If you disagree with the adjustment, contact the IRS within 60 days with documentation supporting your position.

What happens if you ignore it?

Penalties and interest accumulate and the account enters the normal collection cycle, eventually leading to levy notices if the balance remains unpaid.

Common resolutions

• Pay the balance
• Dispute the changes

Related IRS notices

• CP21A — Adjusted Return — Refund Due
• CP22A — Adjustment — Amount Due
• CP11 — Changes to Tax Return — Amount Owed
• CP23 — Estimated Tax Payment Discrepancy