As a business expands across borders, products, and sales channels, indirect tax starts to play a bigger role. One of the first signals of that shift is when the business is issued a goods and services tax (GST) number. This tax identifier determines when a business must charge GST, how it reports that tax, and how it recovers GST paid on expenses.

Below, we’ll explain how GST registration works, when it becomes mandatory, and how a GST number works across different countries.

What’s in this article?

• What is a GST number?
  
• Which businesses need to register for a GST number?
  
• What are the attributes of GST numbers?
  
• How does a GST number work in practice?
  
• What does a GST number do for a business?
  
• What happens if a business operates without a GST number?
  
• How Stripe Tax can help
  

What is a GST number?

A GST number is a unique identifier given to a business. It connects that business to a country’s goods and services tax system. Once a business registers for GST, the tax authority issues it a GST number to track the taxes relevant to that business’s sales and purchases. Countries such as Australia, Canada, India, New Zealand, and Singapore use GST numbers.

Which businesses need to register for a GST number?

GST registration is based on what you sell, where you sell it, and how much revenue you generate. In some situations, specific thresholds determine when it’s time to sign up. In others, it depends on the business category.

Here’s who has to register:

• Businesses that exceed a registration threshold: Most GST systems set a revenue threshold. Once taxable sales go over that threshold, registration becomes mandatory. These thresholds vary by country and are usually measured over a rolling 12-month period. Businesses must continuously monitor revenue to determine whether they have crossed the threshold and thus need to register.

• Businesses that expect to exceed the threshold soon: In several jurisdictions, registration is based on reasonable forecasts in addition to past sales. If signed contracts, future commitments, or known expansion plans indicate that the business will cross the threshold, registration is required in advance.

• Businesses making taxable supplies: When you sell goods or services that are classified as taxable under local law, GST registration applies. Even small or early-stage businesses can fall into this category as long as what they sell is subject to GST and other conditions are met.

• Foreign or nonresident businesses selling locally: Many countries require overseas businesses to register for GST when they sell to local customers, even if they don’t have a physical presence. This is especially common for digital services, software, and cross-border ecommerce.

• Online sellers and marketplace participants: In some jurisdictions, selling through online marketplaces requires GST registration regardless of revenue. Rules might apply differently depending on whether the marketplace collects tax on your behalf or shifts that responsibility to sellers.

• Businesses operating across state or regional boundaries: Certain tax systems require a business to register for GST as soon as it sells across internal borders, even if the total turnover is low. These rules make sure taxes are properly allocated between regions.

• Businesses undertaking specific regulated activities: Businesses in some industries are required to register for GST from their first sale. These often include transportation services, import-export operations, and platform-based companies.

• Businesses that choose to register: Companies below the mandatory threshold can register voluntarily. This usually happens when businesses want to claim input tax credits, work with GST-registered clients, or prepare for near-term growth.

What are the attributes of GST numbers?

GST numbers can be numeric or alphanumeric. Within jurisdictions, most follow a fixed character length and have the same internal structure. Some segments might encode particular information, such as the country, region, or business type. The GST number often builds on an existing national business ID, which helps tax authorities connect GST activity to other official filings, such as corporate registrations or income tax accounts.

The same GST number should be used for a business’s invoices, receipts, tax returns, refund requests, and official correspondence. In many jurisdictions, anyone can verify whether a GST number is valid by using online tools provided by the tax authority. A GST number usually remains active until the business deregisters or the tax authority cancels it. After cancellation, the number remains in the historical tax record.

How does a GST number work in practice?

A GST number works across sales, accounting, reporting, and compliance. It connects everyday activity to the overall tax system.

Here’s what businesses with a GST number can (and often must) do:

• Charge GST on taxable sales: From the effective registration date, the business must apply GST to eligible goods and services at the correct rate.

• Collect GST on behalf of the government: GST collected from customers is not business revenue. It should be held in trust until it’s reported and remitted, which is why many businesses track GST separately from their operating cash.

• Record GST paid on business expenses: When a registered business pays GST to suppliers, that tax is recorded as input tax. Proper documentation supports future credit claims.

• Claim input tax credits: On each GST return, the business offsets GST collected on sales against GST paid on eligible expenses. Generally, only GST-registered businesses can do this.

• File periodic GST returns: Businesses must submit GST returns on a defined schedule, often monthly or quarterly. These returns summarize taxable sales, GST collected, credits claimed, and the overall amount payable or refundable.

• Apply GST correctly across borders: When businesses sell internationally, the GST number helps determine where tax applies and where it does not.

Many businesses configure their GST number in invoicing and payment platforms so that tax is calculated and displayed automatically. Stripe Tax, for example, allows businesses to store tax registrations and apply GST logic at checkout and on invoices, which reduces manual handling and error risk.

What does a GST number do for a business?

A GST number gives tax authorities a clear way to see who’s collecting tax. It also provides businesses with a formal mechanism to charge, report, and recover GST correctly.

Here’s what GST registration allows for:

• Legally charging GST on sales: A business cannot collect GST unless it has an active GST number. Charging GST without registration is not allowed in most jurisdictions.

• Linking tax collection to a specific business: A business’s GST number ties every taxable sale, return, and payment to a single legal entity. This allows tax authorities to reconcile what a business charges with what it reports and remits.

• Claiming input tax credits: GST systems are designed to allow businesses to recover GST paid on eligible expenses. A GST number is required to claim those credits. This system prevents GST from becoming a cumulative cost as goods and services move through the supply chain.

• Meeting contractual expectations: Many businesses require their suppliers to be GST-registered.

• Supporting documentation requirements: Most invoices require a valid GST number to be considered complete. Without one, customers might not be able to claim their own credits, which could cause disputes.

• Ensuring transparency: Registration allows tax authorities to cross-check filings across supply chains. This transparency helps to reduce errors, leakage, and fraud.

• Enabling oversight: Tax authorities use businesses’ GST numbers to administer audits, issue refunds, apply penalties, and communicate compliance obligations.

What happens if a business operates without a GST number?

Businesses that are required to have a GST number shouldn’t operate without one. Doing so risks financial penalties.

Register correctly to avoid the following:

• Retroactive tax obligations: Authorities can retroactively register a business from the date it should have been registered. Businesses then must pay all the GST that should have been charged during that period, even if customers were never billed for it.

• Interest and penalties: Late registration typically incurs interest on unpaid GST, as well as additional penalties. These amounts accrue over time and can quickly outpace the original tax owed.

• Lost tax credits: GST paid on business expenses while unregistered might not be recoverable. What should have been a pass-through tax becomes a permanent cost.

• Invoice and payment issues: Invoices issued without a valid GST number might be treated as noncompliant. Business customers might not be able to claim credits, which can delay payments or complicate contracts.

• Forced registration and extra scrutiny: Tax authorities might register the business without its involvement, which comes with immediate deadlines for filings and payments. The added attention can also lead to audits.

• Logistical disruption: Missing registration can interfere with platform access, cross-border sales, procurement, and customer onboarding. Registering in advance is often much simpler than dealing with these problems later.

How Stripe Tax can help

Stripe Tax reduces the complexity of tax compliance so you can focus on growing your business. Stripe Tax helps you monitor your obligations and alerts you when you exceed a sales tax registration threshold based on your Stripe transactions. In addition, it automatically calculates and collects sales tax, VAT, and GST on both physical and digital goods and services—in all US states and in more than 100 countries.

Start collecting taxes globally by adding a single line of code to your existing integration, clicking a button in the Dashboard, or using our powerful API.

Stripe Tax can help you:

• Understand where to register and collect taxes: See where you need to collect taxes based on your Stripe transactions. After you register, switch on tax collection in a new state or country in seconds. You can start collecting taxes by adding one line of code to your existing Stripe integration or add tax collection with the click of a button in the Stripe Dashboard.

• Register to pay tax: Let Stripe manage your global tax registrations and benefit from a simplified process that prefills application details—saving you time and simplifying compliance with local regulations.

• Automatically collect tax: Stripe Tax calculates and collects the right amount of tax owed, no matter what or where you sell. It supports hundreds of products and services and is up-to-date on tax rules and rate changes.

• Simplify filing: Stripe Tax seamlessly integrates with filing partners, so your global filings are accurate and timely. Let our partners manage your filings so you can focus on growing your business.

Learn more about Stripe Tax, or get started today.