IRS notice CP503

Second reminder of balance due

The second reminder that you still owe a balance on one of your tax accounts.

What to check on your letter

The notice code in the top right corner
The amount shown and whether it is a bill or a proposed change
The date printed on the letter to respond or pay by

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OweRight is not affiliated with the IRS. This page explains the notice in general. It is not tax, legal or financial advice. Last checked October 5, 2026.