Entering an incorrect Social Security number (or other identifying number) on a return is a simple, preventable mistake that commonly delays processing. Tax agencies match submitted returns to informational forms (W-2s, 1099s) using these identifiers; mismatches require manual review, which slows refunds and can produce confusing notices. Before filing, verify the SSN, legal name spelling, and dependent identifiers against official documents and employer records. For e-filers, tax software often pre-fills or validates these fields, but human verification remains critical — small transposition errors or copy-paste mistakes happen.

Other easy checks that prevent delays include confirming routing and account numbers for direct deposit, ensuring signatures on paper returns, and validating dependent information. Keep digital or physical copies of key ID documents in your tax folder for quick reference. If you discover an error after filing, act promptly: contact your preparer or the tax authority for instructions on correction — quick fixes reduce confusion and minimize processing lag. Building a small pre-filing checklist (SSNs, names, bank details, and critical forms) eliminates many common headaches.