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CP501, explained

First reminder you still owe.

Updated October 8, 2026Fact checked
How urgentMedium

First reminder you still owe.

The short answer

A CP501 is a reminder that you still owe. The IRS sends it when it has not seen a payment or a reply to an earlier notice. Interest keeps growing. If you don't pay or reply, the IRS can file a federal tax lien.

Key facts

  • It follows an earlier bill, like a CP14.
  • Interest and more penalties keep adding up.
  • The IRS can file a federal tax lien if you don't act.
  • You can ask for a Collection Appeals Program appeal before collection starts.

Where it falls

  1. 1. CP14First bill for unpaid tax
  2. 2. CP501First reminder you still owe
  3. 3. CP503Second reminder you still owe
  4. 4. CP504Notice of intent to levy
  5. 5. LT11 or Letter 1058Final notice of intent to levy and your right to a hearing

What to do next

  • Pay by the due date on the notice.
  • Can't pay it all? Apply for a payment plan online or mail Form 9465.
  • Disagree? Call the number on the notice.

Check your balance in your own IRS online account, and use the phone number on the notice or on irs.gov.

Results depend on your situation. Not every case qualifies.

Common questions

What is a CP501 notice?

A CP501 is a reminder that you still owe. The IRS sends it when it has not seen a payment or a reply to an earlier notice. Interest keeps growing. If you don't pay or reply, the IRS can file a federal tax lien.

How urgent is a CP501?

Medium. Act by the date on the notice so it does not move up the ladder. The date on your notice is the one that counts.

Run the numbers with our free tax tools, like the penalty and payment plan math.

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Free to use. Not the IRS or any government agency. Results depend on your situation. Not every case qualifies.