Letter 525

A Letter 525 transmits the results of a mail audit: enclosed is Form 4549, the examination report, listing each proposed adjustment and why. It is called a 30-day letter because of the window it opens — 30 days to agree, push back with documentation, or take the case to the IRS Independent Office of Appeals.

“Our examination proposes these specific changes, itemized in the enclosed report. If you agree, sign and return the agreement form. If you disagree, respond by the due date with documentation, ask for the examiner's manager, or request an Appeals conference in writing. Need more time? Call before the due date and ask.”

The 30 days is the negotiating window: inside it, disagreement goes to documentation, a manager conference, or Appeals. If it closes unanswered, the next letter is typically a statutory notice of deficiency — the same dispute, now on a rigid 90-day court clock. Extensions can be requested by calling before the due date.

• The letter and the enclosed Form 4549 examination report
• Your return and the records behind each adjusted item
• Everything already sent to the examiner, so nothing is re-litigated from scratch
• A clear list of which adjustments you'd concede and which you'd contest

• Reading the examination report the way examiners write them — knowing which adjustments are soft
• Preparing the Appeals request (Form 12203 for smaller cases) with reasons that carry weight
• Negotiating with the examiner's manager before Appeals is even needed
• Protecting the timeline so the case never reaches the 90-day letter unresolved