Pull all three reports first
You have three credit files — Equifax, Experian, and TransUnion — and they rarely match. An account can report cleanly on one bureau and show a false late payment on another, which is why checking only one bureau misses problems.
Get your reports for free at AnnualCreditReport.com (the only federally authorized site). Read each line: account names, open/closed status, balances, payment history, and the personal information at the top.
Flag what's actually disputable
You can dispute anything inaccurate, incomplete, or unverifiable: accounts you don't recognize, balances you already paid, duplicate collections for the same debt, late marks on months you paid on time, or a wrong name or address.
You cannot dispute accurate negative information away. A late payment that really happened, or a collection you truly owe, is not an 'error' — though you have other options for those, like goodwill requests or pay-for-delete negotiations.
Send the dispute in writing — and keep proof
You can dispute online, but a written dispute by certified mail with return receipt creates a paper trail: proof of what you sent and the date the bureau received it. Include your name, the specific item, why it's wrong, and copies (never originals) of any supporting documents.
Under the Fair Credit Reporting Act, the bureau generally has 30 days (up to 45 in some cases) to investigate. If the furnisher can't verify the item, it must be corrected or removed.
After the investigation
The bureau must send you the results in writing and a free updated report if anything changed. If an item is fixed on one bureau, dispute the same item on the others — corrections don't sync automatically.
If a verified error comes back 'verified' anyway, you can add a 100-word statement to your file, escalate to the furnisher directly, or file a complaint with the CFPB.
You can do every step above yourself, for free — the law gives you the right. What an app like Subefy adds is speed: it reads all three reports, flags what's disputable, drafts the letters, and tracks each 30-day deadline. Results vary, and no specific outcome is guaranteed.