Notice Type
Letter 12C means the IRS needs additional information or documentation before it can finish processing your return, often because a form is missing, an entry needs verification, or something on the return didn't match IRS records. Your return stays on hold until the requested information is provided, and this type of notice often fits within our standard $45 notice review as a starting point, since it usually begins with understanding exactly what's being requested.
Before You Respond
Letter 12C means the IRS won't finish processing your return, or release any refund, until you respond, so responding is what moves things forward. Check the response date printed on your actual letter — Letter 12C generally states a deadline for providing the requested information, and that date is what determines your timeline, not a general rule of thumb. If the requested information isn't provided by that date, the IRS may process the return using only the information it already has, which can change the outcome, including any refund. Responding with what's requested by the date on your letter keeps the return moving toward completion.
Know Before You Act
Before responding, it helps to understand exactly what the letter is asking for, since Letter 12C requests are usually specific to one form, entry, or piece of documentation. The IRS may just need something straightforward, like a missing schedule or a copy of a form already filed. But there can also be a document that was never issued, information that's genuinely missing from the return, or a mismatch that needs a closer look. Knowing which of these applies to your situation is what determines how to respond.
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.