Inland Revenue Authority (IRAS Portal): Your Guide to Singapore Tax Administration

IRAS is the main tax collection agency of Singapore that administers corporate tax on income, GST, withholding tax,  IRAS income tax, and stamp duties via IRAS Singapore’s entirely digital and compliance-focused framework that focuses on accuracy, transparency, and digital readiness in invoicing.

Key takeaways

• Registration of GST is mandatory when the amount of turnover to be subject to tax is more than SGD 1 million.
• InvoiceNow is the national Singapore-based e-invoicing system, which is gradually being enforced on GST-registered organizations to enhance GST compliance.
• IRAS myTax Portal is a centralized system of registration, filing, payment, refunding, and official communication procedures of businesses.
• Documentation, readiness of systems, and compliance in good time are very strong measures of minimizing audit risk and penalties.

What is the Inland Revenue Authority of Singapore (IRAS)?

The Inland Revenue Authority of Singapore is a government statutory body under the Ministry of Finance that manages and enforces Singapore's tax laws. It evaluates, gathers and controls taxes on individuals and businesses, as well as retaining trust in the tax system of Singapore.

In addition to tax collection, IRAS is instrumental in developing a predictable, technology-based compliance environment. Its focus on digital filing, structured data as well as e-invoicing helps Singapore to create the image of a transparent and business-friendly jurisdiction.

What are the Core Roles and Responsibilities of IRAS?

IRAS operates a fully integrated digital ecosystem that centralises tax administration and minimises manual compliance work.

1. Digital Access and Authorisation

Most business compliance happens through myTax Portal, which is  a secured portal to manage tax transactions - MyTax Portal. Access to many IRAS digital services requires authorisation via CorpPass (authorising employees/third parties to transact). 

2. Filing, payment, and account management

IRAS runs official workflows to:

• File returns (GST returns, corporate filings, etc.). 
• Pay taxes / manage GIRO and balances through digital services that point users back into myTax Portal. 

3. Guidance and Interpretations

IRAS publishes detailed e-guidance through its e-Tax Guides  library (technical interpretations, principles, and conditions). 

4. Corrections and voluntary disclosures

IRAS provides formal routes to correct errors and potentially reduce penalties when qualifying conditions are met, including GST-specific and broader voluntary disclosure guidance. 

5. Strategic objectives

• Preserve tax integrity while reducing administrative burden for compliant businesses.
• Promote voluntary self‑assessment supported by data‑driven controls.
• Strengthen Singapore’s standing as a trusted global business hub.

Key Taxes Administered by IRAS [With Official Links]

The Inland Revenue Authority of Singapore is the primary tax administrator for Singapore and manages the end-to-end compliance lifecycle for businesses. Below are the key taxes (and compliance obligations) IRAS administers

1. Corporate Income Tax Compliance

Corporate Income Tax applies to company profits, with a flat rate of 17% on chargeable income for both local and foreign companies. 

What IRAS administers and enforces

• Filing obligations and timelines (e.g., filing requirements and common compliance issues are centrally explained under IRAS corporate tax resources). 
• Tax assessments, notices, and dispute workflows handled through digital services (viewing notices/letters, responding, and managing corporate tax transactions via the business account). (MyTax)
• Compliance programmes and error correction approach, including voluntary disclosure pathways and “common errors to avoid.” 

Important Links

• Use the Corporate Income Tax hub for filing/compliance guidance. 
• Refer to the official Corporate Income Tax rates page for the 17% rate and related rate items. 

2. GST Compliance

GST is Singapore’s consumption tax. The current GST rate is 9%, and GST-registered businesses must charge/account for GST on taxable supplies unless a supply is zero-rated or exempt under GST rules. 

GST Registration (compulsory and prospective triggers)

IRAS requires GST registration if taxable turnover exceeds the threshold:

• Retrospective view: taxable turnover more than S$1 million assessed at the end of the calendar year. 
• Prospective view: you can reasonably expect taxable turnover to be more than S$1 million in the next 12 months (and must apply within the stated timeframe). 

Official reference: Do I need to register for GST? 

GST Filing and administration

What IRAS administers and enforces

• Quarterly GST return filing through IRAS e-filing processes (including guidance on how to file via myTax Portal). 
• GST digital services for registration, filing status, document submission, notices/letters, etc. 
• Correction mechanisms such as GST F7 workflow for disclosures/corrections (where applicable). 
• Voluntary disclosure programme routes for GST errors, including penalty treatment based on timing and qualifying conditions. 

3. Withholding Tax Compliance

Withholding tax applies to certain payments to non-residents, especially where services are rendered in Singapore or where payments fall into categories that are taxable under withholding rules.

What IRAS administers and enforces

• Clarifies which cross-border payments are subject to withholding tax and the general principle that payments to non-resident persons for services rendered in Singapore are typically in scope. 
• Requires businesses to withhold the correct amount, file, and pay within prescribed timelines (and maintain supporting documentation for the position taken).

4. Stamp Duty Compliance

Stamp duty applies to various dutiable instruments/transactions (commonly property-related and share-related documents). IRAS provides the official stamping and duty payment workflows.

What IRAS administers and enforces

• Assessment and payment of stamp duties.
• Digital stamping (e-Stamping) and the ability to retrieve/verify stamping records and certificates (where relevant). 

Official Links

• How to e-stamp and available channels: e-Stamping and where to e-Stamp documents 

5. Property Tax Compliance

Property tax is based on a property’s Annual Value (AV). IRAS explains how AV is determined and applies tax rates accordingly. 

What IRAS administers and enforces

• Annual Value determination approach and AV checks. 
• Property tax rates and billing (for business contexts, non-residential properties such as commercial/industrial properties are taxed at 10% of AV, per IRAS’s property tax rate page). 

Official references

• Rates: Property Tax Rates and Sample Calculations 
• Annual Value concept: About Annual Value 

InvoiceNow e-Invoicing for GST Compliance

IRAS is implementing the GST InvoiceNow Requirement, under which GST-registered businesses must transmit invoice data to IRAS using InvoiceNow-ready solutions via the InvoiceNow network. 

InvoiceNow is in IRAS context

IRAS explicitly describes InvoiceNow as Singapore’s nationwide e-invoicing network based on the Peppol standard, introduced by the Infocomm Media Development Authority, enabling structured digital invoicing. 

Who must Comply with InvoiceNow and When

IRAS sets a phased mandate (focused first on new voluntary GST registrants):

• From 1 November 2025: companies that register for GST voluntarily within 6 months of being incorporated. 
• From 1 April 2026: all new voluntary GST registrants, regardless of incorporation date. 

IRAS also notes a soft launch from 1 May 2025 and encourages early adoption. 

IRAS Official reference links

• Main requirement and rollout: GST InvoiceNow Requirement 
• Practical onboarding guidance (soft launch + steps): Prepare early and adopt the GST InvoiceNow Requirement from 1 May 2025 

What are the Best practices for IRAS compliance?

Effective compliance with IRAS requirements depends on strong internal controls, system readiness, and regular monitoring.

Recommended Practices

• File all tax returns and make payments within statutory deadlines.
• Maintain complete, verifiable records aligned with IRAS documentation standards.
• Use InvoiceNow‑ready accounting systems for GST invoicing.
• Perform periodic internal reviews and reconciliations.
• Seek professional advice for complex transactions or regulatory changes.

Common Compliance Risks

Conclusion

IRAS Singapore sits at the centre of Singapore’s highly structured, digital-first tax system. To businesses, compliance is about doing the right calculations along with system integration, quality information and process discipline.