What CP166 means
CP166 says the IRS tried to withdraw your monthly installment payment and could not, because there was not enough money in the bank account. The IRM describes it as the notice that a direct debit installment agreement payment was dishonored for insufficient funds.
Your agreement is not automatically over. But it is now under strain, and how fast you respond decides whether it survives.
Internal IRS procedures describe CP166 as a notice on business (BMF) accounts. If you have an individual agreement and got a similar message, the steps below still apply, but read the notice you have.
Why you got it
A direct debit installment agreement authorizes the IRS to pull a fixed amount from your bank account on a set date every month. The IRS page for CP166 is blunt: once you set it up, the IRS will try to withdraw the payment on the scheduled date, every month, even if you mailed a payment separately.
Common causes are predictable:
- A deposit landed a day after the debit date.
- You changed banks and the IRS still had the old account.
- You mailed a check thinking it replaced the debit, then the debit hit a near-empty account.
- Another automatic payment drained the account first.
What to do now
- Make the missed payment. The IRS page says to make a payment if you haven't already. Do it right away and keep the confirmation.
- Check the account on file. If the IRS tried an old account, update your agreement. The IRS says you can verify and update a direct debit agreement through the Online Payment Agreement tool.
- Fix the timing. If the debit date does not line up with when money arrives, change the date. The IRS says the Online Payment Agreement tool can do that too.
- Talk to your bank. If you are sure the funds were there, the IRS says to contact your bank. Any bank fee for the failed debit is between you and the bank.
- Watch your mail. If the agreement was cancelled, the IRS says you can use the Online Payment Agreement tool to reinstate it.
The dishonored payment penalty
IRC 6657 applies to any payment made by a commercially acceptable means that is not honored, not just paper checks. The penalty is 2 percent of the payment amount. If the payment is less than $1,250, the penalty is $25 or the amount of the payment, whichever is less.
The statute has a built-in exception. It does not apply if you tendered the payment in good faith and with reasonable cause to believe it would be paid. The IRS page for CP166 says that if you believe you have a valid reason, you may qualify for penalty relief. A documented bank error is the classic example. A paycheck that posted late may or may not be enough, so explain the facts and keep your records.
A bounced IRS payment costs you twice: once in the penalty, and once in the goodwill your agreement depends on.
How close is default?
Internal IRS procedures treat a rejected debit as a skipped payment, and repeated rejected debits can cause the agreement to default. The exact internal count is not something you should test.
The statute gives you some protection. IRC 6159(b)(4) lets the IRS alter, modify, or terminate an agreement when you fail to pay an installment when due. But IRC 6159(b)(5) requires written notice at least 30 days before that action, explaining why. If you receive a proposed termination notice, such as a CP523, read its appeal instructions immediately.
Interest and penalties keep running
The IRS page notes that you may owe additional interest and penalties. An installment agreement does not freeze the balance. Interest and applicable late payment penalties continue on the unpaid amount until it is paid in full. A missed month means a slightly larger balance and a longer road.
What not to do
Do not mail a check and assume the debit will be skipped. The IRS has said it will still try.
Do not close the old bank account before the IRS has the new one on file.
Do not ignore the notice because you plan to catch up next month. Two problems in a row are harder to explain than one.
Prevent the next one
Set the debit date a few days after your regular deposit lands. Keep a cushion in that account equal to at least one payment. If your income has dropped and the payment no longer fits, ask for a revised agreement before the next debit rather than after it bounces. Our guide to installment agreement letters explains the related notices you may see.
The IRS page also offers a tip worth repeating for next year: adjust withholding or make estimated tax payments so you do not build a new balance while paying off the old one. A second balance can put an existing agreement at risk.
A quick word about the bank fee
Your bank may charge its own fee for the failed debit. That is separate from anything the IRS charges. The IRS page for CP166 says that if your bank charged a fee because the IRS tried to withdraw from an old account, you need to contact your bank to have it waived. The IRS cannot remove a bank's fee, and the bank cannot remove the IRS penalty.
Records to keep
- The CP166 and the date you received it.
- Confirmation of the make-up payment.
- Bank statements for the month of the failed debit, showing the balance on the debit date.
- Any letter from the bank admitting an error.
- Screenshots or confirmations of changes you made to the account or payment date.
Those records are what a penalty relief request is built on. Without them, it is your word against the IRS's computer.
The law behind CP166
IRC 6657 imposes the dishonored payment penalty and its good-faith exception. IRC 6159(b)(4) and (b)(5) govern when the IRS can modify or terminate an agreement for a missed installment and the 30-day notice it must give first. IRM 21.3.1.7.23 describes how the IRS handles CP166 contacts and points to IRM 20.1.10.7 for the dishonored payment penalty.
If your agreement is wobbling and you want help keeping it in place, call us at (813) 229-7100.