If your business needs to file for GST in Singapore, accuracy and timing matter. Late or incorrect submissions can lead to IRAS penalties. This guide explains what to file, when to file it, and how to do it right, stress-free.
GST filing snapshot
- File GST quarterly within 1 month after each accounting period
- Use the GST F5 return to report sales, purchases, output & input tax
- Late filing incurs IRAS penalties
- Keep records tidy & use IRAS-compliant software to avoid errors
- Correct filing mistakes in the next return or via GST F7
- InvoiceNow e-invoicing will be mandatory for some, starting 1 November 2025
What is GST filing, and why does it matter
GST filing is a legal requirement for all GST-registered businesses in Singapore. Every quarter, you must declare the GST you’ve collected from customers and paid on business expenses, even if your sales were zero.
Timely, accurate filing keeps your business compliant, helps you avoid costly IRAS penalties, and ensures you get any GST refunds you’re entitled to. It’s a non-negotiable part of doing business in Singapore.
Whether you’re a café owner in Tanjong Pagar or a SaaS founder working from home, GST filing is a must. It’s essential for staying compliant with Singapore’s tax laws.
Helpful guide - Common penalties for companies in Singapore
Singapore GST filing deadlines: What to know
GST-registered businesses in Singapore must file returns every quarter. Here’s what you need to remember:
- Filing frequency: Quarterly
- In some cases, IRAS may approve annual GST filing, typically for small businesses with low turnover. This must be formally requested and approved.
- Deadline: One month after the end of each accounting period
- Example: If your quarter ends on 30 June, the filing deadline is 31 July
- Penalties: Penalties apply for late filing. See ‘Consequences of late or incorrect GST filing’ for full details.
- Important: IRAS imposes penalties whether your business was active or not
Staying on top of your filing dates helps you avoid unnecessary fines and compliance issues.
‘Quarter’ refers to any 3-month accounting period your business uses. Many businesses use March, June, September, and December year-end quarters, but this is not mandatory.
How to file GST return in Singapore (Step-by-step)
Filing your GST return isn’t complicated, but it does require focus. Here’s a step-by-step breakdown to help you get it right:
- Gather your documents: Collect all your sales invoices, receipts, expense records, and anything showing GST collected or paid.
- Calculate your GST: Work out the following –
- Output tax: GST collected on your sales
- Input tax: GST paid on eligible business expenses
- Log in to myTax Portal: Head to myTax Portal and sign in with your CorpPass. Select the GST F5 return under the GST tab.
- Fill out the GST F5 return: Enter your figures in the right boxes (we’ll cover this next). Double-check your numbers and supporting documents.
- Submit your return: Once done, submit the form. You’ll receive an acknowledgement; save it in your records.
How to file GST F5 return
The GST F5 return is where you report your GST activity for the quarter. It contains several boxes, but don’t worry, not all apply to every business. Here are the key ones to focus on:
Key Sections of the GST F5 Return (What to Focus On)
Box No. | What It’s For | What to Include |
Box 1 | Total Value of Standard-Rated Supplies | The sale value before GST for goods/services subject to GST |
Box 6 | Output Tax Due | Total GST collected from customers |
Box 7 | Input Tax and Refunds Claimed | GST paid on business expenses you’re eligible to claim |
If you enter incorrect values, like including GST in Box 1 or claiming non-eligible expenses in Box 7, IRAS may delay your refund, request clarification, or trigger an audit.
While the form includes other boxes (like exempt or zero-rated GST supplies), most small businesses only need to focus on Boxes 1, 6, and 7.
Double-check your numbers, organize your records, and only claim what’s supported by valid tax invoices.
Consequences of late or incorrect GST Filing
Mistakes or delays in filing your GST return can be costly:
- Late filing penalty: $200 per full month late, capped at $10,000 per return.
- Estimated tax assessments: If you don’t file, IRAS may issue a bill based on past data. You’ll still need to file the actual return and settle any differences.
- Audits or investigations: Repeated errors, suspicious claims, or late filings can trigger a full audit.
- Court action: In serious or repeated non-compliance cases, IRAS may:
- Appoint agents (e.g., banks or employers) to recover unpaid tax
- Issue Travel Restriction Orders
- Take legal action
Avoiding this is simple: file on time, file accurately, and review before submitting.
Fixing errors in your GST return
Made a mistake? IRAS provides clear steps to correct it:
1. Minor errors: Small discrepancies (e.g., rounding or input tax tweaks) may be adjusted in your next GST F5 return, if:
- The net GST error across affected periods is S$3,000 or less, and
- Other box errors (excluding Boxes 6, 7, and 12) are within 5% of the total value in Box 4 (or Box 5 if no supplies were made).
2. Major errors: Significant issues, like wrong figures, omitted invoices, or ineligible claims, must be corrected using a GST F7 form. IRAS expects serious errors to be fixed within 30 days of discovery, along with supporting documents and explanations.
Don’t leave errors unaddressed as they can lead to penalties. If you're not sure how to amend your return, Sleek’s accounting team can help you fix it quickly and correctly.
Best practices to file GST accurately in 2026
Here’s how to keep your GST return clean, compliant, and audit-ready:
- Prepare and organise your documents: Keep all invoices, receipts, and credit notes in one place, preferably in digital format. IRAS may request them years later.
- Ensure access and system readiness: Check that your login works. Using IRAS-compliant accounting software helps reduce errors and keeps records aligned.
- Be aware of filing deadlines: Your GST return is due one month after your quarter ends. Mark the date to avoid last-minute issues and penalties.
- Double-check your GST calculations: Use the correct GST type, claim only valid input tax, and make sure Boxes 1, 6, and 7 are accurate.
- Get a second opinion if needed: If you’re unsure, Sleek’s GST team can review your return or help fix errors using the GST F7 form.
- Submit and save your return: File via the myTax Portal and save the acknowledgement receipt as proof of submission.
Before you hit “submit,” use this checklist to stay compliant, organised, and stress-free:
Special cases in Singapore GST filing
Not every GST return is straightforward. Some situations need a little extra attention, and getting them wrong can lead to unnecessary penalties or delays.
Here are a few special cases to be aware of:
1. Nil returns
Even if your business had no transactions in a quarter, you still need to file a return. Just enter ‘0’ in all relevant boxes. Skipping this is treated as late filing.
2. GST refunds (Tourist Refund Scheme)
If your business is part of the Tourist Refund Scheme, you’ll need to report GST refunds properly. IRAS has strict documentation rules, so make sure claims are valid and supported.
Note: This scheme applies only if your business is part of IRAS’s Tourist Refund Scheme. Most small businesses don’t qualify unless they serve tourists and meet specific IRAS criteria.
3. Voluntary GST registration
If you registered for GST voluntarily (below the $1M turnover threshold), you still have to file quarterly returns just like everyone else, even with low or no activity.
Once voluntarily registered, your business must remain GST-registered for at least 2 years, unless IRAS approves deregistration earlier.
4. InvoiceNow requirement (Starting Nov 2025)
Starting 1 November 2025, newly incorporated companies that voluntarily register for GST must adopt InvoiceNow e-invoicing. From 1 April 2026, this requirement applies to all new voluntary GST registrants, regardless of when the company was incorporated. This means sending invoice data to IRAS digitally through approved software.
How Sleek can help you file for GST
From GST quarterly filing to annual returns, Sleek keeps your business on track with IRAS. Here’s how we help:
- File F5 return accurately and on time
- Review or amend past returns (GST F7)
- Ensure GST compliance with IRAS rules
- Support special cases like voluntary registration and InvoiceNow
Whether you need us to handle everything or just check your numbers before IRAS does, we’re here to help. Our local GST experts have your back, so you can file right, avoid fines, and stay focused on running your business.
Need help with your GST numbers?
FAQs on GST filing in Singapore
What’s the difference between the GST F5 and F7 forms?
The GST F5 form is used for your regular quarterly GST return. It reports your taxable supplies, GST collected (output tax), and GST paid on business expenses (input tax).
The GST F7 form is used when you need to amend a previously submitted GST F5 return due to an error. This form allows you to correct under- or over-reported figures.
Can I file my GST return myself?
Yes, you can file your GST return directly via the IRAS myTax Portal using your CorpPass. However, it’s your responsibility to ensure all amounts are accurate and that only eligible input tax is claimed. Many businesses use a provider like Sleek to avoid mistakes, especially when they’re new to GST or pressed for time.
I registered for GST voluntarily. Do I still have to file?
Yes, voluntary GST registration comes with the same responsibilities as compulsory registration. That means you must file quarterly GST returns, even if your revenue hasn’t reached the S$1 million threshold.
What’s InvoiceNow, and how does it affect my GST filing?
InvoiceNow is Singapore’s e-invoicing framework, designed to let businesses send invoice data directly to IRAS through approved digital platforms. Starting 1 November 2025, newly incorporated companies that voluntarily register for GST must adopt InvoiceNow. This requirement expands further from 1 April 2026, when all new voluntary GST registrants, regardless of incorporation date, must also use InvoiceNow.
While InvoiceNow doesn’t replace GST filing, it helps standardise digital invoicing, reduce manual errors, and streamline compliance with IRAS.
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