GST registration, filing and InvoiceNow: Frequently asked questions

GST registration, filing and InvoiceNow together form the compliance backbone for any Singapore business handling taxable turnover: registration becomes compulsory once turnover exceeds S$1,000,000, quarterly F5 returns must be filed within one month of each accounting period, and InvoiceNow e-invoicing is progressively becoming the default channel for GST-registered businesses transacting with government and, over time, with each other.

What GST registration, filing and InvoiceNow actually cover

Goods and Services Tax (GST) is a broad-based consumption tax charged on the supply of goods and services in Singapore and on the import of goods, administered by the Inland Revenue Authority of Singapore (IRAS). A business becomes a “taxable person” once it is registered, and from that point it must charge GST on standard-rated supplies, claim input tax on business purchases, and file periodic returns. InvoiceNow is Singapore’s nationwide e-invoicing network, built on the Peppol framework, that transmits structured invoice data directly between accounting systems rather than as PDF attachments or paper. Since 1 November 2025, newly incorporated GST-registered companies have been required to use InvoiceNow for transmitting invoice data to IRAS as part of the GST reporting process, with the requirement extending progressively to existing GST-registered businesses.

These three strands (registration, periodic filing, and InvoiceNow transmission) are increasingly treated as a single compliance workflow by IRAS, because the e-invoicing data is used to pre-fill and cross-check GST returns.

Who this applies to

Compulsory registration applies to any business, whether a company, partnership or sole proprietorship, whose taxable turnover exceeds the prescribed threshold on either a retrospective (past 12 months) or prospective (next 12 months) basis. Voluntary registration is open to businesses below the threshold that want to recover input tax, typically exporters, businesses with mostly GST-registered customers, or those investing heavily before generating taxable revenue. InvoiceNow obligations currently bite hardest for newly incorporated GST-registered entities and larger established businesses that IRAS has notified directly; smaller existing registrants are being brought in on a phased timetable that businesses should monitor via the IRAS website.

Eligibility and requirements: numbers that matter

Beyond the headline turnover threshold, several secondary numbers determine how registration and filing play out in practice, and these are the figures that catch most first-time registrants off guard.

  • Compulsory registration threshold: taxable turnover exceeding S$1,000,000 in the past 12 months, or reasonably expected to exceed S$1,000,000 in the next 12 months.
  • Standard GST rate: 9 percent (with effect from 1 January 2024).
  • Voluntary registration: available below the S$1,000,000 threshold, subject to a minimum two-year commitment and, in most cases, a director/sole-proprietor GST e-learning course plus, where required, a banker’s guarantee.
  • Filing frequency: quarterly for most businesses, with the F5 return due one month after the end of each accounting period.
  • Record-keeping: underlying transaction records and tax invoices must be retained for at least 5 years.
  • InvoiceNow rollout: compulsory for newly incorporated GST registrants from 1 November 2025, with existing registrants phased in over subsequent tranches announced by IRAS.

Cost and timeline

Registration itself is free when applied for directly via myTax Portal, and IRAS typically processes complete applications within 10 working days, longer if additional information or a guarantee is requested. Engaging a corporate services firm to prepare and submit the application typically costs between S$300 and S$800 depending on complexity. Ongoing quarterly filing, if outsourced, commonly runs from S$150 to S$600 per return depending on transaction volume and the state of the underlying bookkeeping. InvoiceNow onboarding, which involves connecting an accounting system or using a free Peppol-ready invoicing solution, is typically a one-off setup exercise of one to three weeks, with several accounting software providers offering no-cost InvoiceNow-ready plans for small businesses.

Step-by-step process

The registration decision itself deserves more attention than most SMEs give it, because the consequences of getting the timing wrong (either registering too late, or voluntarily registering without a clear commercial reason) are asymmetric: late registration triggers penalties and retrospective GST liability, while premature voluntary registration locks a business into filing obligations and a two-year minimum term. A short internal review each quarter, comparing rolling 12-month turnover against the S$1,000,000 threshold on both a retrospective and prospective basis, is the cheapest way to avoid both traps.

  1. Determine liability. Track taxable turnover monthly; the moment the retrospective or prospective threshold is breached, registration must be applied for within 30 days.
  2. Apply via myTax Portal. Submit the GST registration application (Form GST F1, or F3 for group registration) with supporting documents such as the latest financial statements, projected revenue, and the applicant’s BizFile business profile.
  3. Complete e-learning where required. Voluntary applicants, sole proprietors and certain first-time company directors must pass the “Registering for GST” e-learning course before approval.
  4. Receive the effective date of registration and GST registration number, and update invoices, contracts and price displays to reflect GST-inclusive pricing from that date.
  5. Set up InvoiceNow. Register the entity on the Peppol network via an accredited access point or accounting software, and map the chart of accounts so invoice data flows correctly into GST reporting.
  6. File each period’s F5 return within one month of period end, reconciling output tax on sales against input tax on purchases and remitting any net GST payable by the same deadline.
  7. Retain records (tax invoices, credit notes, import permits, InvoiceNow transmission logs) for at least 5 years in case of an IRAS audit.

Common mistakes and gotchas

The most frequent error is late detection of the registration trigger: businesses that only review turnover annually often breach the prospective 12-month test without noticing, resulting in late-registration penalties and GST that IRAS deems to have been payable from the date liability arose, even if it was never collected from customers. A second common mistake is treating InvoiceNow as optional once a business decides it prefers PDF invoices; for entities within a mandated tranche, non-compliance can affect the accuracy of pre-filled GST returns and invite IRAS queries. Businesses also frequently under-claim input tax by failing to retain proper tax invoices, or over-claim by including disallowed expenses such as private motor car costs and club subscriptions, which are specifically excluded under GST regulations. Finally, many SMEs miss the requirement to display prices inclusive of GST at the point of sale, which is a distinct compliance obligation from the return-filing cycle itself.

A further recurring issue is inconsistent treatment across group entities. Where a company operates several related entities, each with taxable turnover below S$1,000,000 individually but combined well above it, IRAS may still look through the arrangement if the entities are effectively a single business split to avoid registration, and directors should be prepared to demonstrate genuine commercial separation. Businesses that voluntarily register also sometimes overlook the two-year minimum registration period, then find they cannot deregister early even if turnover falls or the business model changes, so voluntary registration should be a considered decision rather than a reflexive one taken purely to look more established to customers.

On the InvoiceNow side, a subtle but costly mistake is assuming that any invoicing software automatically produces a compliant Peppol document. Not all software is Peppol Ready, and businesses that switch accounting systems mid-year sometimes discover, only when a customer or IRAS rejects a transmission, that the new system was never properly connected to an access point. Building a short reconciliation step, comparing InvoiceNow transmission logs against the sales ledger each quarter before the F5 return is filed, catches this early rather than at year-end.

The most frequent error is late detection of the registration trigger: businesses that only review turnover annually often breach the prospective 12-month test without noticing, resulting in late-registration penalties and GST that IRAS deems to have been payable from the date liability arose, even if it was never collected from customers. A second common mistake is treating InvoiceNow as optional once a business decides it prefers PDF invoices; for entities within a mandated tranche, non-compliance can affect the accuracy of pre-filled GST returns and invite IRAS queries. Businesses also frequently under-claim input tax by failing to retain proper tax invoices, or over-claim by including disallowed expenses such as private motor car costs and club subscriptions, which are specifically excluded under GST regulations. Finally, many SMEs miss the requirement to display prices inclusive of GST at the point of sale, which is a distinct compliance obligation from the return-filing cycle itself.

How this interacts with corporate tax and cross-border hiring

GST compliance rarely sits in isolation. Businesses restructuring for tax efficiency, including family offices considering the 13O/13U/13D schemes, still need a clean GST position across any operating entities before a restructuring is finalised; see our related guide on how to apply for GST registration in Singapore. Businesses scaling headcount alongside GST registration also need to plan their Employment Pass and work-permit pipeline in parallel; our partner site’s guide on spouse work eligibility across pass types is a useful cross-reference for founders relocating key hires at the same time as scaling turnover past the GST threshold.

FAQs

Do I need to register for GST if my turnover is below S$1,000,000?
No, registration is not compulsory below that threshold, but voluntary registration is available if it suits your business model, for example if most of your customers are GST-registered or you export goods and services.

What happens if I register for GST late?
IRAS may impose a penalty and will still require GST to be accounted for from the date your liability arose, meaning you may need to absorb the GST cost yourself if you did not collect it from customers in the interim.

Is InvoiceNow the same as filing my GST return?
No. InvoiceNow transmits structured invoice data to support and pre-fill GST reporting, but the GST F5 return itself is still a separate periodic submission on myTax Portal.

Can I deregister from GST if my turnover falls?
Yes, if taxable turnover is not expected to exceed S$1,000,000 going forward, a business may apply to deregister, though IRAS will review the last two years of returns before approving this.

Which authority do I contact for GST registration or InvoiceNow queries?
IRAS handles registration and filing queries directly, while InvoiceNow technical onboarding support is coordinated through the Infocomm Media Development Authority’s Peppol Ready programme, referenced from the IRAS and gov.sg InvoiceNow pages.

Additional considerations for growing businesses

As a business approaches the S$1,000,000 threshold, it is worth reviewing pricing structures well in advance, since GST-inclusive pricing changes customer-facing quotations and contracts, not just back-office accounting. Businesses with significant zero-rated exports should also consider whether early voluntary registration allows them to recover input tax sooner, which can materially improve cash flow during a scaling phase. Where a business operates internationally and receives services from overseas suppliers, it should also review whether reverse charge obligations under the overseas vendor registration regime apply in parallel with its own local GST registration, since these are separate but related compliance streams within the same GST Act framework.

Finally, businesses preparing for their first GST audit should treat InvoiceNow transmission records as part of their core audit trail alongside tax invoices and bank statements, since IRAS increasingly cross-references these data sources when reviewing a return.

Related guides

For a deeper walkthrough of the registration mechanics, see our companion piece, GST registration, filing and InvoiceNow: Common mistakes and rejection reasons. Statutory registration thresholds are set out in the First Schedule to the Goods and Services Tax Act 1993, and the requirement for GST-registered persons to issue proper tax invoices is set out in section 33(1) of the Goods and Services Tax Act 1993; both should be read alongside current IRAS e-Tax Guides, which are updated more frequently than the underlying statute. For authoritative detail, refer to IRAS, the Ministry of Finance, and ACRA.

Need help with this? Call, SMS or WhatsApp +65 8501 7133, or email [email protected]. Raffles Corporate Services works with a panel of corporate and employment law firms; this article is general information, not legal advice.