Notice Type
A CP523 or CP623 notice means the IRS believes you've defaulted on an existing installment agreement, often because a payment was missed, a new tax return created an additional balance, or updated financial information wasn't provided. It warns that the agreement may be terminated and gives you a window to fix the issue before that happens, and this type of notice often fits within our standard $45 notice review as a starting point, since it usually begins with understanding what triggered the default and confirming whether it's accurate.
Before You Respond
A CP523 or CP623 means your current payment plan is at risk of being terminated, so addressing it quickly is what keeps the agreement in place. Check the date printed on your actual notice — these notices state a specific date by which you need to respond or resolve the issue to prevent termination, and that date is what determines your timeline, not a general rule of thumb. If no response is made by that date, the IRS can terminate the installment agreement, and the full remaining balance becomes due, which can lead to further collection action, including a levy. Acting before that date is what keeps the existing agreement, or the option to set up a new one, available.
Know Before You Act
Before assuming the default is accurate or letting the deadline pass, it helps to understand two things: what specifically triggered the notice, such as a missed payment or a new balance, and whether that matches your own records of what was paid and filed. The IRS may be correct about the default. But there can also be a payment that was sent but not applied, a new balance from a return that hasn't been reviewed yet, or a request for updated information that was missed. Knowing which of these applies to your situation is what determines whether the agreement can be preserved or needs to be renegotiated.
Start with a secure notice upload and a free IRS notice summary. If you want organized next steps, optional $45 Review & Guidance is a one-time purchase with no subscription. It may include an Action Plan, records to gather, response options, and case questions. When the information and supporting documents provided support a written IRS response, you can use the action steps provided to prepare it yourself or unlock the option for Think Twice Tax to draft a personalized response letter for you.