Canada GST Verification: Using Official Registry (+ Automation)

Every business owner knows their major costs, like payroll, rent, and inventory. But what if an invisible expense was quietly draining your profits every month? For many Canadian businesses, it is.

This cost comes from denied Input Tax Credits (ITCs), all because of one unchecked detail on supplier invoices: an invalid GST number. Every time you pay an invoice with a bad number, you lose the right to claim that tax back.

This guide is about making that invisible expense visible and then eliminating it for good.

We’ll walk you through the simple, official way to verify every supplier’s GST number so you can be confident you’re getting back every dollar your business is owed.

Canada Revenue Agency (CRA) Requirements for GST Number Verification

The rules for a supplier’s GST number verification seem straightforward, but the Canada Revenue Agency (CRA) looks at more than just the number itself. Your ability to claim back the GST you pay depends on getting a few key details right, all of which are based on Canada’s Excise Tax Act.

The CRA takes this seriously because the entire tax credit system is built on trust. For them, an invalid GST number is a major red flag for fraud. Their main job is to confirm that every credit you claim is tied to a real purchase from a legitimate business.

Therefore, you need to confirm three things that prove you’ve done your due diligence to protect your ITCs:

1. Verify the GST Number

The CRA expects you to be the one to check the facts. They will not accept “my supplier told me it was correct” as an excuse. You have to take reasonable steps to verify every GST number on every invoice you receive.

2. Confirm Active Registration Status

A valid GST number isn’t valid forever. You must confirm the supplier was actively registered on the exact date of your transaction. If their registration was inactive, your ITC claim for that purchase is invalid.

3. Match the Legal Business Name Exactly

The final detail is precision. The legal business name on the invoice must match the name tied to that GST number in the CRA’s database perfectly. A trade name or even a small typo can be a red flag in an audit.

Overlooking these details has a clear consequence: the CRA can deny your ITC claim, forcing you to absorb the cost.

Essential Information to Collect from Suppliers

Getting your verification right starts with collecting the right information from your suppliers before you process a payment. Here’s what you should have on file for every vendor:

• Complete Business Number: This is the full 15-character number, not just the 9-digit registration. The format is 123456789RT0001, where the “RT” identifies it as a GST/HST account.
• Exact Legal Business Name: You need the legal name of the business as registered with the CRA. This is often different from the operating or trade name they use on their website.
• Registration Effective Date: This is the date the supplier’s GST/HST registration became active. It helps you confirm they were registered to collect tax when your transaction occurred.
• Primary Business Address: You should have the physical location of the business that is on file with the CRA.
• A Compliant Invoice: For any taxable supply over $30, the supplier must provide an invoice that includes their full GST/HST number. Check that this appears correctly on all documents.

Having these details organized makes the verification process smooth and provides a clear audit trail for your own records.

Use the CRA GST/HST Registry for Verification

The official way to verify a supplier’s GST number is by using the free online GST/HST Registry provided by the Canada Revenue Agency (CRA). This is the government’s direct source of truth and works perfectly if you’re only checking a few suppliers here and there.

However, if your business deals with dozens or hundreds of vendors, doing this one by one is a huge time sink. The good news is that tech solutions use the very same CRA database, so you get the same accuracy without manual effort (we are going to discuss this in the next section).

Here are the steps to use the official registry.

Step 1: Get Your Information Ready

Before you start, you’ll need three key pieces of information from the supplier’s invoice:

• The supplier’s 9-digit Business Number (BN)
• The exact business name
• The date the transaction occurred

Step 2: Perform the Search on the Registry

Go to the CRA’s GST/HST Registry page. You’ll see a straightforward form where you can enter the supplier’s information.

Step 3: Check the Results and Keep a Record

The tool will immediately tell you if the information you entered matches an active GST/HST registration for that date. It’s a good practice to print or save a screenshot of this confirmation page as proof of your due diligence.

If the online tool gives you an error or the results are confusing, the next step is to contact the CRA by phone at their Business Enquiries line: 1-800-959-5525. Just make sure to have all the supplier’s details with you before you call.

Automation Solutions for High-Volume GST Verification

Does your team spend hours every month on the CRA website, checking GST numbers one by one? If so, you’re not alone.

Frankly speaking, it’s a slow, repetitive task that creates a bottleneck, delaying payments and opening the door to costly human errors. That is not a scalable way to run a growing business.

Smart businesses take a different approach. They use an automated verification platform to turn a compliance headache into a seamless background task.

Here’s what that actually does:

• Clear Your Invoices Instantly: Instead of one-by-one checks, you can verify hundreds of supplier GST numbers at once just by uploading a file. What used to take hours now takes minutes.
• Stop Problems at the Source: By connecting directly to your accounting software, verification happens automatically when you add a new vendor, catching issues before you make a payment.
• Get an Ironclad Audit Trail: Automation eliminates the risk of typos and creates a perfect, timestamped record of every check. This gives you a solid audit trail for compliance to prove your due diligence to the CRA.

APIs are probably your best bet for this kind of automation.

Rather than building something from scratch or sticking with manual verification, you can plug into existing solutions that already do the work and scale with you.

We’ve actually tackled this exact problem for our clients and built our Canada GST Verification API specifically for businesses dealing with high-volume GST checks. If you are looking to streamline the manual GST checking, book a demo here to learn more about how you can free your AP team’s time.