IRS NOTICE REFERENCE
Understanding your CP166 notice
We couldn’t withdraw your monthly payment because there wasn’t enough money in your bank account.
General information only. Not legal or tax advice.
Notice details
- Notice code
- CP166
- Category
- Installment agreement and collection alternatives
- Severity tier
- Tier 2 — Action or response expected. The IRS has taken or proposed an action and expects a response or payment.
- Governing law
- §6159 (Internal Revenue Code section)
- Source
- IRS.gov — Understanding Your IRS Notice
What this notice is
We couldn’t withdraw your monthly payment because there wasn’t enough money in your bank account.
Source: IRS.gov. Reproduced for reference. General information — not legal or tax advice.
What the IRS says to do
If you haven’t already, make a payment . Each month, make sure there's enough money in your bank account to cover your monthly Direct Debit Installment Agreement (DDIA) payment by the due date.
This is the IRS’s own guidance reproduced from the IRS notice page. It describes the IRS’s process — it is not legal or tax advice from TaxRiskOS.
Governing IRS procedure (Internal Revenue Manual)
The IRS’s own internal procedures for handling this notice type are documented in the Internal Revenue Manual:
- IRM 5.14.1 — 5.14.1 Securing Installment Agreements
- IRM 5.14.5 — 5.14.5 Streamlined, Guaranteed and In-Business Trust Fund Express Installment Agreements
- IRM 5.14.2 — 5.14.2 Partial Payment Installment Agreements and the Collection Statute Expiration Date (CSED)
Reference to published IRS procedure. General information — not legal or tax advice.
Official IRS reference
Read the official notice page on IRS.gov: https://www.irs.gov/individuals/understanding-your-cp166-notice
Related tools
TaxRiskOS is workflow software for practitioners — it captures the notice, computes the deadline, surfaces the escalation tier, and builds a document checklist. It documents process; it does not give advice or draft responses.
Check this notice’s deadline (free tool)