What the bureaus legally have to do when you dispute
Section 611 forces an investigation within 30 days. Here's exactly what triggers it and what counts as a valid response.
When you mail a written dispute to Equifax, Experian, or TransUnion, you are not asking for a favor. You are triggering a federal obligation. Under Section 611 of the Fair Credit Reporting Act (15 U.S.C. §1681i), the bureau must conduct a 'reasonable reinvestigation' of the item you challenged, and it has 30 days from the day it received your letter to complete that process.
The 30-day clock starts when the dispute arrives, which is why we use certified mail with tracking. If you add information to your dispute mid-investigation, the bureau gets 15 extra days. If you never hear back, or if the response is late, the item must be deleted — not merely flagged or hidden, deleted from your file.
During the reinvestigation, the bureau is required to forward all the relevant information you provided to the furnisher (the creditor or collector). The furnisher then has to investigate on its end and report back. If the furnisher cannot verify the item, or simply does not respond in time, the bureau is required to remove the item from your report.
A valid response from the bureau is not 'we verified this account.' That phrase alone means nothing. The response must include the results of the reinvestigation, a fresh copy of your credit report if anything changed, and notice of your right to add a 100-word statement and to request a description of how the verification was done.
If the bureau replies that your dispute is 'frivolous,' that is a stall tactic you can answer in writing. A dispute is only legally frivolous when it lacks any factual basis. Including the account number, the specific inaccuracy, and the reason it is wrong almost always defeats a frivolous designation and forces the investigation to begin.