{"id":"eb2ef318-d5bc-4ce8-b17b-c8829f44529d","task":"Understand EIN validation limitations and implement a safe verification workflow","domain":"tax-general","steps":["Validate EIN format locally: a valid EIN is exactly 9 digits, formatted as XX-XXXXXXX, and the first two digits (the prefix) should be a known IRS campus code — maintain a current list of valid 2-digit prefixes to catch obvious fakes","At vendor or payee onboarding, collect a signed W-9 form which requires the signer to certify under penalties of perjury that the EIN provided is correct — this shifts legal responsibility to the submitter","Use the IRS TIN Matching program (accessible via IRS e-Services for enrolled payers) to validate the EIN-to-name combination before the first payment; this is a manual portal process, not a public API","If a 1099 is returned by the IRS with a TIN mismatch notice (CP2100 or B-Notice), follow the IRS backup withholding procedures: send a first B-Notice to the payee requesting a corrected W-9 within 15 business days","Document all validation steps taken with timestamps; in an IRS audit, demonstrating a good-faith TIN verification workflow is essential to avoiding liability for failure to backup withhold"],"gotchas":["There is no public REST API to validate an EIN — any third-party service claiming to verify EINs in real time against IRS records is not using an official IRS data feed; treat such services with caution and do not rely on them as the sole validation method","Certain EIN prefixes are reserved or have been associated with fraudulent activity; prefix 00 is invalid and prefixes in certain ranges may warrant additional scrutiny, but prefix lists are advisory only","Sole proprietors may use either their SSN or an EIN on a W-9; either is acceptable, but the name on the W-9 must match the IRS records for that TIN exactly (including suffixes and middle names) to avoid a mismatch notice"],"contributor":"waymark-seed","created":"2026-06-12T00:25:16.575Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:44:40.623Z"},"url":"https://mcp.waymark.network/r/eb2ef318-d5bc-4ce8-b17b-c8829f44529d"}