GST Tax Invoice Requirements for Singapore [2025]

Business owners know the importance of a professional and compliant approach to administration - particularly when it comes to invoicing. There are many different types of invoices which can be used in different situations. But if you’re a GST registered business in Singapore, you need to know and apply the GST tax invoice requirements to capture all the required details.

This guide gives an introduction to the Singapore tax invoice requirements including how to figure out what GST to add. We’ll also touch on Wise Business as a financial solution to help you simplify your invoicing process while ensuring you get the mid-market rate for any foreign currency transactions.

This guide is for information only - if you’re unsure about any of the requirements for GST for your Singapore business, seek professional advice to make sure you comply with the law.

What is the difference between a tax invoice and a standard invoice?

A standard invoice is used to confirm the sale of goods and services. A tax invoice on the other hand is used when tax - like GST (Goods and Services Tax) in Singapore - needs to be added into the amount you collect from your customer when they pay.

A tax invoice is a little different to a standard invoice, although both invoice types may look similar and fulfil the same basic requirement.

A tax invoice must contain crucial information such as your business GST registration number, and the amount of GST you’re collecting on the sale. You must hold GST invoices for at least 5 years. Although you don’t then need to submit each invoice to IRAS when you file your GST on a quarterly basis, you might need the invoices for your own records or if you’re ever audited by IRAS¹.

Generally, all businesses need to be creating and issuing sleek and professional invoices. This creates a good impression with customers and can make record keeping easier too. By issuing an easy to understand invoice, on time and on brand, you make it easier for your customer to pay you, helping your cash flow and giving your business a boost.

If you’re issuing tax invoices in Singapore you need to get familiar with the IRAS tax invoice requirements. The good news is that the rules for GST invoicing are very clearly set out allowing business owners to follow a step by step guide, while also adding their own branding and identity to professional invoices.

When and why should you issue a tax invoice?

📝 If you are a GST registered company dealing with customers who are also GST registered, you must issue a tax invoice when you sell goods or services which are eligible for GST.

📝 If you’re selling to a non GST registered customer you can choose to issue a receipt instead. There are also some options for simplified tax invoicing if you’re billing smaller amounts which we’ll look into a little later.

When you sell to a GST registered company, you must issue your GST invoice 30 days from the time of supply. Time of supply can be a little tricky to calculate in some cases but it’s generally the earlier of when payment is received or when an invoice is issued. If you’re billing on a continuous basis you can use this rule of thumb - generally the sooner you can issue your invoice, the better, as you’ll know it’s a job done and one less thing to worry about.

Details to include in a tax invoice in Singapore

While your tax invoice can be made to look on brand for your business, there are some important pieces of information which must be contained on it.

There are 2 kinds of tax invoices - the standard tax invoice which can be issued on all sales and which must be issued if the value of the sale is 1,000 SGD or above - and the simplified invoice structure. Simplified invoices are intended for smaller sales under 1,000 SGD, to make the administration process a little easier. We’ll cover simplified invoices a little later.

IRAS states that all standard tax invoices issued in Singapore must include the following information:

• The words ‘tax invoice’
• Supplier’s name and address
• Supplier’s GST registration
• Invoice date
• An identifying number
• Customer name and address
• Description of the goods sold
• Total amount being charged excluding GST
• GST rate
• Total GST payable
• Total payable including cost of goods and GST

As long as you have all of this detail contained in your invoice, you can then add your own branding and other details, including a message to the customer. This will allow you to balance a compliant, branded and professional looking approach to tax invoicing, no matter what business you run.

How to calculate GST on tax invoices

IRAS allows for 2 different methods of calculating the GST you need to collect from customers. You can choose which one you prefer, but you should then use it consistently. There may be slight differences in the amount you get using the different methods - essentially rounding errors - so choosing one and sticking with it is the best option.

Here are the methods IRAS can accept to calculate GST on tax invoices:

• Apply 9% to the value of each item (excluding GST), and then sum the GST computed for each item
• Apply 9% to the sum of the value of all items (excluding GST)

Once you’ve calculated GST, you can round the total to be paid to the nearest cent, or if you take customer payments in cash you can round your total bill to the nearest 5 cents. As a business you can decide whether you’re rounding bills up or down, but again, it’s best to be consistent in your approach here.

When to issue simplified tax invoice

If the total amount of your invoice - that is, the value of goods and services, plus GST - is under 1,000 SGD, you can choose to issue a simplified tax invoice. This is still compliant and might save you a little time. In this case, the information needed on a simplified tax invoice in Singapore is:

• Supplier's name and address
• Supplier's GST registration number
• Date of issue of invoice
• An identifying number
• Description of the goods or services
• Total amount payable including GST
• The words ‘price payable includes GST’

A simplified tax invoice can still be sleek and professional and include your own company branding. By creating an invoice which represents your brand you’re communicating with your customers - and by making your invoice easy to read and pay you should get your money more quickly in the end, too.

Conclusion

Understanding the nuances of invoicing, particularly tax invoices, is crucial for businesses aiming to ensure compliance and optimise their financial operations in Singapore

For Singapore-based businesses, adhering to guidelines such as those provided by IRAS, and the local GST regulations is particularly important.

GST Tax Invoices might have a lot of details to take care of but it doesn't have to be daunting. This guide covers all the basics and there’s also plenty of advice available direct from IRAS or through local professional tax accountants. Use this guide to GST invoicing in Singapore to make sure you’re issuing easy to read, compliant and professional invoices for all your sales - and don’t forget to also take a look at Wise Business for great ways to manage your business transactions across currencies with fair rates and low fees.

• Hold and manage 40+ currencies for all your international transactions
• Pay suppliers and receive payments internationally without the hefty foreign transaction fees
• Always get the mid-market rate with zero markup
• Seamless integrations with popular accounting software
• Say goodbye to monthly fees

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Sources checked on 18th March 2025