Tax Identification Number

A Tax Identification Number (TIN) in Nigeria is issued by the Federal Inland Revenue Service (FIRS) for companies and by the relevant State Internal Revenue Service for many individuals, depending on your tax status.
If you are an individual:
Register with your State Internal Revenue Service (or through your employer if you’re in paid employment).
Provide:
A valid means of identification (National ID, Voter’s Card, International Passport, or Driver’s Licence)
Your National Identification Number (NIN), where applicable
Proof of address
Passport photograph (if requested)
Once your registration is processed, a TIN is generated for you.
If you own a registered business:
After registering your business with the Corporate Affairs Commission (CAC), you can obtain a TIN through FIRS. For many newly registered businesses, the TIN is now generated as part of the business registration process.
If you only want to verify or retrieve an existing TIN, you can use the official FIRS TIN verification portal:
apps.firs.gov.ng
If you tell me which applies to you:
an individual (salary earner),
a public servant,
a business owner, or
someone registering a new business,
I can give you the exact steps for your situation.