Every minute a business spends waiting on a failed or delayed TIN check is a minute you risk losing that business. In Nigeria's fintech space, onboarding friction isn't just a mere inconvenience but a conversion risk for your platform.

Verifying Tax Identification Numbers (TIN) is a standard step in KYB and an important part of maintaining a reliable onboarding flow. Most teams approach this in two ways, but only one works effectively when you need to scale.

This article breaks down how each method works, where each fits, and why most digital products end up choosing one over the other.

What you need before verifying a TIN

Before verifying a TIN, have these details ready to reduce failed checks and make verification smoother within your onboarding flow.

1. TIN — Ensure the number is correct and complete before submitting. For individuals, the 11-digit NIN may serve as the Tax ID; registered businesses typically use their CAC registration number.

2. Basic business or individual information — The official registered name of the business or individual, used to cross-check records during verification.

3. Access to a verification method — Either the FIRS Taxpromax portal for manual checks, or an API-based verification service for automated checks.

Method 1: manual TIN verification (FIRS)

Manual TIN verification is the traditional approach, where checks are done directly through government channels. It works at low volumes, but the cracks show quickly as onboarding grows.

The step-by-step process

1. Head to the FIRS portal or a physical tax office — This is where all manual verification requests are initiated and processed.

2. Input the TIN details — Enter or submit the TIN you want to verify. Accuracy matters here, as any incorrect input affects the outcome.

3. Wait for validation — The system processes the request and returns a response. This may take time, depending on traffic and request volume.

4. Match the information — Compare the returned details with the business or individual information you have on file.

Method 2: API-based TIN verification

API-based TIN verification lets you validate tax records automatically within your product. Instead of handling checks manually, verification happens in the background as users submit their details. 

Most teams building at scale implement this through verification APIs like Dojah, which connects directly to FIRS records without requiring any manual intervention.

How the automated flow works

1. Input — The user enters their Tax ID (NIN or CAC number) during onboarding. Verification begins immediately as part of data collection.

2. API request — Your system sends the submitted data to a verification API instantly in the background.

3. Validation — The API checks the TIN against authoritative FIRS data sources to confirm validity and match business details.

3. Response — The API returns a structured result. Your system uses this to either proceed with onboarding or surface a correction prompt — without dropping the user into a manual queue.

Manual vs API TIN verification

At scale, manual verification doesn’t just slow you down; it becomes your major onboarding challenge. Every additional hire to handle the queue is a cost that an API eliminates.

How to choose the right TIN verification method

Use manual verification if:

• You are verifying fewer than 50 businesses per week, and checks are handled internally before users are activated.

• Your onboarding process is not fully digital and does not require instant results.

• You are in early-stage testing and not yet ready to build a full verification infrastructure.

Use API-based verification if:

• You are building a fintech or digital-first product where users expect registration and verification to be completed in minutes.

• Your system needs to make real-time onboarding decisions,  passing or flagging a user before they reach the next step.

• You are handling growing volumes where manual checks cannot keep up. Verifying 5,000 businesses manually requires a large ops team; API verification handles the same volume automatically.

A useful rule of thumb: if your onboarding SLA is under 10 minutes, manual verification will break it. If you are onboarding more than a few hundred businesses a month, the ops cost of manual checks will exceed the cost of an API integration within the first quarter.

How Dojah automates TIN verification in onboarding

Connecting to an API is the easy part. The harder part is building a verification layer that handles edge cases; mismatched names, stale records, partial data, without requiring manual fallback.

Dojah provides KYB infrastructure that plugs TIN verification directly into your onboarding flow, with real-time validation against FIRS records. When a TIN check runs, Dojah validates the submission and returns structured data, including:

• Taxpayer name — the registered legal name of the entity

• CAC registration number — for cross-referencing the CAC registry

• Tax office — the assigned FIRS tax collection centre

• Contact details — phone number and email associated with the business

• TIN format check — structure and consistency validation of the submitted TIN

 See the full setup instructions, including sandbox access in the  Dojah's API docs. 

If manual verification is slowing your onboarding or increasing ops overhead, see how Dojah handles TIN verification in real time,  from a single API call to a full KYB flow.

Book a demo →

Frequently asked questions

1. How do I verify a TIN in Nigeria?

You can verify a TIN online via the FIRS TIN Verification Portal or the Joint Tax Board (JTB) site using an 11-digit NIN for individuals or a CAC Registration Number for businesses. For automated verification within a product, use a KYB API like Dojah’s.

2. What happens if the TIN doesn’t match the business name?

A mismatch usually means the business name has changed since registration, the name was entered with a variation (e.g. “Ltd” vs “Limited”), or the TIN belongs to a different entity. A good verification API returns the registered name alongside the result so you can surface a correction prompt rather than simply rejecting the user.

3. Is TIN verification mandatory for KYB in Nigeria?

TIN verification is not always a standalone legal requirement, but it is a standard component of KYB due diligence for fintechs operating under CBN guidelines. Most compliance frameworks require it as part of confirming that a business is legitimately registered and tax-compliant before onboarding.

4. Can TIN be verified via API?

Yes. Identity providers like Dojah offer KYB APIs that connect directly to FIRS records, allowing you to automate tax ID checks during user registration.

5. Is a TIN enough for business verification?

No — a complete KYB process also includes verifying CAC registration status, identifying company directors and ultimate beneficial owners (UBOs), and performing AML screening.

6. Can I verify a TIN without a CAC number?

In most cases, yes — TIN verification can be run using just the TIN or NIN. However, combining it with a CAC number significantly improves match accuracy for registered businesses, since it allows the system to cross-reference two independent data points.