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IRS notice decoder · Bills for a balance due

CP501: a reminder that a balance is still unpaid

A CP501 is a reminder: an earlier bill went unpaid or unanswered. Here is how to check the balance and pay or set up a plan by the date on it.

By the Carry Forward Learning team Reviewed by Hunter Nottingham, JD, CPA

No dated figures Checked Review by

CheckedOct 19, 2026

What a CP501 means

A CP501 is a reminder that you owe a balance on one tax account. The IRS says it sent it because it hasn't received payment, or an answer, to an earlier notice asking for payment. source 1

In the usual order it follows the CP14, the first bill. It is firmer than the first bill but it is still a bill, not a levy notice.

We read a CP501 as the same question the CP14 asked, now with interest still running: is this amount right, and how will it be paid?

The date that counts

Pay by the due date shown on the notice. The IRS page gives no other window. Interest is charged on the unpaid balance until it is paid in full, and the IRS says contacting it by the due date may help with removing the failure-to-pay penalty, depending on your situation. source 1

Why people get one

  • A first bill for the balance went unpaid or unanswered.
  • A payment was sent but hadn't posted, or was applied to a different year, when the notice went out.
  • A balance was left after the IRS changed something on the return.

First steps

  1. Find the tax year and the amount, then put the notice beside your return for that year.
  2. Check your IRS online account (typed in yourself at irs.gov) to confirm the notice is real and see the balance and any payments already posted. source 1
  3. If the amount is right, pay it by the due date on the notice, online or by mail with the bottom part of the notice. source 1
  4. If you can't pay it all, apply online for a payment plan or mail Form 9465. source 1
  5. If you disagree, call the number printed on your notice with your records in front of you, such as canceled checks. source 1
  6. Keep the notice and a note of what you did and when.

What not to do

  • Don't ignore it. The IRS says it may file a federal tax lien, which can affect your credit, and interest keeps running. source 1
  • Don't pay through a link or phone number from an unexpected email or text. Use irs.gov, typed in yourself.
  • Don't treat a payment plan application as a payment. Until it is approved, pay what you can.

Where it sits

When a balance stays unpaid

The usual order of the bills and collection notices. Not everyone gets every step, so the code on your letter is what tells you where you are.

  1. CP14First bill
  2. CP501ReminderYou are here
  3. CP503Second reminder
  4. CP504Notice of intent to levy
  5. LT11Final notice of intent to levy, with hearing rights
  • Comes before CP14 The first bill for the balance.
  • Can come next CP503 The second reminder if the balance stays unpaid.

Keep reading

Questions

Is a CP501 the same as a CP14?

No. The IRS describes the CP501 as a reminder sent because it hasn't received payment or an answer to an earlier notice asking for payment. source 1

What happens if I don't pay a CP501?

The IRS says it may file a federal tax lien, a public claim to your current and future assets that can affect your credit, and that interest keeps accruing and more penalties may apply. source 1

I think the CP501 is wrong. What do I do?

The IRS says to call the number on the notice with supporting records ready, and to file Form 1040-X if the return itself needs correcting. source 1

Sources

  1. IRS, Understanding your CP501 notice (updated July 22, 2026) (external site) checked Oct 19, 2026

Every rule on this page comes from the IRS page in the list, read on the date shown. Your notice itself is the final word on its own dates and amounts.