An Employer Identification Number uses the XX-XXXXXXX shape. The first two digits identify an IRS assignment prefix, so test fixtures should use permitted prefixes instead of arbitrary nine-digit strings.
Create mock company fixtures
The EIN Generator can select an IRS campus group, mock state and company name. Exports retain the EIN together with company, state and campus fields so onboarding fixtures keep their context.
Keep test and production data separate
An IRS-compatible format does not mean an EIN was issued. Mark generated rows as synthetic, keep them in non-production datasets and validate input shape again at the system boundary.
Validate mixed fixtures
Use the Tax ID Validator to check individual values. The local report explains format and checksum outcomes without uploading identifiers.