If your business is registered for GST (Goods and Services Tax), your invoices must meet specific legal requirements. Here's what to include, common mistakes to avoid, and how to stay compliant.
What Is GST?
Goods and Services Tax (GST) is a broad-based consumption tax applied to most goods and services sold in GST-implementing countries. It goes by different names in different places — VAT (Value Added Tax) in Europe and the UK, GST in Australia, New Zealand, Canada, India, Singapore, and others — but the underlying principle is similar: a tax collected at each stage of the supply chain.
As a GST-registered business, you collect GST from your customers on behalf of the government and periodically remit the collected amount (minus what you've paid to your own suppliers) to the tax authority.
This guide uses GST terminology but the principles apply equally to VAT-registered businesses.
Do You Need to Be GST-Registered?
Most countries have a registration threshold — an annual turnover above which registration is mandatory. Below that threshold, registration is often optional.
Examples:
Once registered, you must collect GST on taxable supplies and issue compliant tax invoices.
What Must a GST-Compliant Invoice Include?
Requirements vary by country, but a standard GST/tax invoice for B2B transactions typically requires:
For B2C transactions (selling to end consumers), simplified invoices with less buyer detail are often acceptable.
Input Tax Credits (ITC)
One of the main benefits of GST registration is claiming input tax credits — the GST you've paid on your own business purchases. You can offset this against the GST you've collected from customers, only remitting the difference.
To claim ITC, you need valid tax invoices from your suppliers. This is why your suppliers' invoices need to be compliant — and why your clients (if they're GST-registered) will insist that your invoices are compliant too.
A non-compliant invoice from you could prevent your client from claiming their input tax credit, which creates friction in your business relationship.
Common GST Invoicing Mistakes
Missing registration number. If your GST number isn't on the invoice, your client can't claim the input credit. This is the most common compliance failure.
Not separating the GST amount. The tax amount must be shown separately — "including 10% GST" in the total isn't sufficient for most jurisdictions. Show: Subtotal, GST Amount, Total.
Wrong rate applied. Different goods and services can attract different GST rates (or be GST-exempt). Using the wrong rate — even if the total amount is the same — creates a compliance problem.
Issuing invoices when not registered. Charging GST when you're not registered is illegal in most jurisdictions. If you're not yet at the threshold, don't add GST to your invoices.
Not keeping copies. You're required to keep copies of all tax invoices issued (and received) for a period set by your jurisdiction — typically 5-7 years.
GST Settings in Quotation Expert
Quotation Expert supports GST/VAT configuration in business settings. You can set your registration number, default tax rate, and choose whether prices are entered as tax-inclusive or tax-exclusive. The tax amount is automatically calculated and shown separately on every invoice — keeping you compliant without manual calculation.
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