Chapter 5

Working out your GST refund or payment

Working out GST is simple maths. Keeping track of all your transactions is the tricky part. Let’s learn the process.

A person on their phone calculating GST

GST is a simple formula

You work out GST by comparing the amount you paid on purchases to the amount you collected on sales.

If you get a positive number, you need to pay that amount to IRAS. If it’s a negative number, you’ll get a refund for that amount.

How to work out GST in four steps

1. Make a note of the GST paid on your business purchases

A GST form indicating GST paid, and a delivery moped

2. Make a note of the GST collected on sales

A GST form indicating GST collected, and some bakery foods

3. Add both types of GST

4. Run the GST formula

Avoid nasty surprises with smart bookkeeping

Like any business, you’ll be aiming to sell more than you buy. If you succeed in doing that, you’re most likely to end up with GST to pay. Run the four-step GST equation regularly so you can see how big your GST payment is shaping up to be.

Automate your GST calculations

You can use online accounting software like Xero to stay on top of GST. It automatically records GST collected and paid, and does the maths for you.

The software keeps a running count of your GST situation so you always know where you stand. It’s IRAS-compliant – when the GST period is over, you simply run the GST F5 in Xero, print it off, and file it with IRAS.


Xero does not provide accounting, tax, business or legal advice. This guide has been provided for information purposes only. You should consult your own professional advisors for advice directly relating to your business or before taking action in relation to any of the content provided.

GST Guide For Business

Making a start with GST? Don’t worry. It’s a little extra admin, but this guide will help you get sorted.

  1. What is GST?

    You’ve probably heard about GST before – it stands for goods and services tax and is added onto prices in Singapore.

  2. Registering for GST

    Find out if your business needs to register for GST. If so, learn how to do it and find out what happens next.

  3. Calculating GST and issuing tax invoices

    If you’re a GST-registered business you must add GST to your prices. You also need to issue GST invoices. Find out how.

  4. Claiming back GST

    GST-registered businesses can claim back the GST they pay on business expenses. Learn when and how.

  5. Working out your GST refund or payment

    Working out GST is simple maths. Keeping track of all your transactions is the tricky part. Let’s learn the process.

  6. GST returns and due dates

    GST-registered businesses must declare how much they’ve collected and paid. You do this by filing GST returns (GST F5).

  7. Tools and guides for your business

    Now you know the ins and outs of GST, but it can be tough to keep on top of it all. Xero’s got the resources to help.

Download the GST Guide for Business

Get your GST sorted. Fill out the form to receive this guide as a PDF.

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