Singapore GST Registration: Step-by-Step Guide for Companies (2026)

GST in Singapore is governed by the Goods and Services Tax Act and administered by the Inland Revenue Authority of Singapore (IRAS). Registration becomes compulsory once your taxable turnover crosses S$1 million, but IRAS applies that single threshold under two separate tests that founders routinely confuse on a first reading.

Under the retrospective view, you assess your taxable turnover for the past calendar year, from 1 January to 31 December. If it exceeded S$1 million, you must apply for registration between 1 and 30 January of the following year, and you are registered on 1 March. Under the prospective view, you assess whether you can reasonably expect your taxable turnover to exceed S$1 million in the next 12 months, and if so you apply within 30 days of that forecast. The two tests run in parallel: liability under either one is enough. Full criteria are on the IRAS GST registration page.

What counts as taxable turnover

Taxable turnover is the total value of your standard-rated and zero-rated supplies made in Singapore. It excludes exempt supplies, such as most financial services and the sale or lease of residential property, as well as out-of-scope supplies and the proceeds from selling capital assets. The distinction matters, because misclassifying exempt or out-of-scope income inflates your turnover and can lead you to register when you do not need to. The official breakdown of standard-rated, zero-rated, exempt, and out-of-scope supplies is on the IRAS GST basics page.

Before you do anything else, run the GST Registration Calculator on myTax Portal. It is the only IRAS-sanctioned way to self-assess which view applies to you, and you will reference its output during the application itself.

All GST registrations are submitted through myTax Portal, using a Corppass login on behalf of the company. Corppass enrolment can take additional time if your company is not yet set up or if your directors are foreign nationals without Singpass, so plan that step ahead rather than discovering it on application day.

Step 1, Run the GST Registration Calculator first

Open the GST Registration Calculator before the application form. It walks through both the retrospective and prospective views and tells you which trigger applies. Save the output as a PDF; it anchors your self-assessment and speeds up the review.

Step 2, Gather supporting documents (mandatory for the prospective view)

If you register under the prospective view, IRAS requires documents that evidence your forecast. Accepted evidence includes signed contracts or agreements, accepted quotations or confirmed purchase orders, invoices with a fixed monthly fee, and income statements showing a past 12-month period already close to S$1 million on an increasing trend. Forecasts based on market assessments, business plans, or sales targets alone are explicitly not accepted, and applications without anchored documents are typically returned for clarification.

Step 3, Submit the e-form

Log into myTax Portal with Corppass and complete the GST registration e-form. It collects your entity details, expected business activities with SSIC codes, estimated future taxable supplies by category, and your bank account details for GIRO.

Step 4, Set up GIRO

IRAS recommends GIRO for GST settlement. The GIRO authorisation is filed in the same session but processed by your bank in parallel, and timing varies by bank, so check with yours directly. Setting up GIRO before your effective date avoids cheque or PayNow workarounds on the first payment.

Step 5, Note your effective date

The effective date, not the submission date, is when GST charging legally begins. Under the retrospective view it is fixed at 1 March of the following year. Under the prospective view, for forecasts on or after 1 July 2025, it is 2 months from your forecast date, which gives you a window to update systems before charging GST. IRAS does not publish a fixed processing time, so do not plan around an assumed turnaround; plan around the effective date, which is fixed.

Step 6, Update invoicing and POS systems

Once you receive the registration confirmation, update all invoicing and POS systems to charge GST at the current 9% rate (effective 1 January 2024, per IRAS current GST rates) and display your GST registration number on every invoice. This is also the point to separate input and output GST in your bookkeeping. If you would rather have this configured for you, you can compare Singapore accounting providers that include GST setup in their onboarding.

Companies below the S$1 million threshold can register voluntarily through the same myTax Portal flow, minus the forecast evidence. The decision is rarely obvious and turns on your customer mix. The official framework is on the IRAS factors-to-consider page.

When it helps

B2B companies serving GST-registered customers benefit, because input GST on business expenses becomes recoverable. A consultancy spending S$50,000 a year on standard-rated inputs such as software, rent, and professional services recovers roughly S$4,500 in input tax, while the output GST it charges is pass-through for GST-registered clients. Exporters and zero-rated suppliers also benefit, since their output is zero-rated but they still recover input GST.

When it hurts

B2C companies and those serving customers who are not GST-registered usually lose out. The 9% you add either reduces your effective revenue or your margin, and input GST recovery only partly offsets it. Model your own numbers, because how much of the 9% you can absorb versus pass on depends entirely on your pricing power.

The 2-year lock-in

IRAS notes that voluntary registration commits you to staying registered for 2 years, and advises assessing the costs and benefits over that full period before electing in. De-registration during the lock-in is generally not permitted except in specific cessation circumstances, so treat it as a 2-year decision, not a reversible experiment.

Once registered, you must charge output GST on taxable supplies, track input GST on purchases, file GST returns, and pay any net GST by the due date.

Filing frequency

Most newly registered companies are assigned a quarterly filing cycle by default, with accounting periods usually aligned to calendar quarters. Each return is due one month after the end of the accounting period. Companies that consistently file refund returns, typical for exporters with large zero-rated output, can apply to IRAS for monthly filing to accelerate refund cash flow.

Invoicing and price display

Every tax invoice must show the words Tax Invoice, your GST registration number, a description of the supply, the 9% GST rate, the GST amount, and your registered company name and address. In B2C contexts, prices shown to consumers must be GST-inclusive, with the GST itemised on the invoice or receipt.

Record retention

GST records, including tax invoices, credit notes, and supporting source documents, must be kept for 5 years, in line with the IRAS invoicing and record-keeping requirements. This sits alongside your other annual obligations, such as ECI within 3 months of your financial year end and the Form C corporate tax filing; see our Singapore ECI filing guide for that part of the calendar. If you would rather not manage GST-compliant invoicing in-house, our Singapore accounting and bookkeeping comparison covers providers that handle it end to end.

Exemption for zero-rated suppliers

Even if your taxable turnover exceeds S$1 million, you can apply for an exemption from GST registration if your zero-rated supplies are more than 90% of your total taxable supplies and you would be in a net refundable position if registered. The application uses Form GST F2. Once exempted, you do not charge GST or file returns, but you also cannot claim input GST on your purchases, so it is a trade-off worth modelling.

Reverse charge and overseas vendor regimes

These regimes have separate thresholds from the S$1 million domestic test. They most often catch SaaS-heavy and digital-first companies importing significant cross-border services. The details and registration triggers are on the IRAS digital economy guidance.

De-registration and cessation

If your taxable turnover falls below S$1 million and is expected to stay there, you can apply to de-register through myTax Portal, provided any 2-year voluntary lock-in has lapsed. Companies winding down must settle outstanding GST returns and payments and de-register before striking off with ACRA, otherwise the cessation process is complicated by an open GST account. If your de-registration is tied to dropping below the small company thresholds, our Singapore small company audit exemption guide explains the related criteria.

1. Submitting prospective-view applications without anchored supporting documents. Internal pipeline forecasts, sales targets, and budget projections are not accepted; only signed contracts, accepted quotations, fixed-fee invoices, or income statements with a documented trend qualify.
2. Confusing the retrospective and prospective windows. The retrospective window is fixed at 1 to 30 January, with a 1 March effective date. Missing the 30 January cutoff risks late-notification consequences.
3. Forgetting the 2-month grace period from 1 July 2025. Many advisory templates still describe the old rule that started GST on the 31st day. For prospective forecasts dated on or after 1 July 2025, GST charging starts 2 months from the forecast date.
4. Setting up GIRO too late. GIRO runs through your bank in parallel with the application, so start it early; if it is not active by the effective date, your first payment needs a manual workaround.
5. Updating invoicing on the wrong date. GST charging starts on the effective date shown in your IRAS confirmation, not the submission date and not the date you receive the letter. Charging early creates a refund obligation; charging late creates a liability.
6. Choosing voluntary registration without modelling the customer-mix impact. For B2C and non-GST-registered customers, the 9% you cannot pass on erodes margin, and the 2-year lock-in makes the decision hard to reverse.
7. Ignoring the reverse charge regime. Companies importing significant overseas digital services may already be liable under reverse charge even when domestic supplies are below S$1 million.