A CP503 Notice is a second reminder that you owe money to the IRS. You should have already received a CP14 or CP501 IRS notice stating that you have a tax balance due. A CP503 means that the IRS still has not received a response or payment and will soon take collections actions if you fail to respond.
CP503 Notice vs. CP503H Notice
Most people who owe tax and didn’t respond to the first notice get a CP503 Notice. This is a general notice that you owe taxes.
If you owe money because of the Shared Responsibility Payment, the IRS sends a CP503H Notice instead.
What if I got a CP503 notice after I already paid?
The IRS takes time to process payments, update tax accounts, and send out notices. Receiving a CP503 may not mean they haven’t received a recent payment or that you still have unpaid taxes.
If you already paid in full or made other payment arrangements, you should call the IRS to confirm you don’t still have an unpaid balance.