Corporate Tax Filing for Singapore Companies
2025 Guide

Last Updated: Nov 2025

Every Singapore company is required to file annual tax returns with the Inland Revenue Authority of Singapore (IRAS) to report its income. Whether your company is newly incorporated, dormant, or fully operational, you must still file an annual income tax return.

This guide explains the key components of Singapore’s corporate tax filing process, including how and when to file the Estimated Chargeable Income (ECI) and the Corporate Income Tax Return.You will learn which forms to use (Form C, Form C-S, or Form C-S Lite), what supporting documents are required, filing deadlines, penalties for late or non-compliance, and practical tips to help company founders stay compliant with IRAS requirements.

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Table of Contents

Quick Summary

Corporate Tax Filing Requirements and Process

Financial Year vs. Year of Assessment Explained

How to File Your Estimated Chargeable Income (ECI)

How to Calculate ECI

When to File ECI

How to File ECI

How to File Your Corporate Income Tax Return

Understanding Form C, Form C-S, and Form C-S (Lite)

Required Supporting Documents

How to File a Corporate Income Tax Return

Penalties for Late or Non-Filing

Special Filing Situations

Practical Tips for Founders

FAQs on Singapore Corporate Tax Filing

Corporate Tax Filing in Singapore

Quick Summary

The corporate tax filing process consists of two main steps: submitting the Estimated Chargeable Income (ECI) and filing the Corporate Income Tax Return.

The ECI provides an early estimate of taxable profits, while the Corporate Income Tax Return reports the company’s actual income and deductions.

Companies file their tax returns using Form C, Form C-S, or Form C-S (Lite), depending on their revenue and filing eligibility.

All corporate income tax returns must be filed electronically by 30 November of the relevant Year of Assessment.

Failure to file on time can result in an estimated tax assessment, composition fines, or court summons issued by IRAS.

Corporate Tax Filing Requirements and Process

Under the Income Tax Act of Singapore, every company incorporated or registered in Singapore must file its annual corporate income tax with the Inland Revenue Authority of Singapore. This requirement applies to all companies, whether they made a profit, incurred a loss, or remained dormant during the financial year.

The annual corporate tax filing in Singapore is composed of two separate filings (ECI filing and Form C filing) as explained below.

1. Submitting the
Estimated Chargeable Income (ECI)

Within three months of its financial year end, every company must file an Estimated Chargeable Income (ECI), a short declaration of its estimated taxable profits. This early filing gives IRAS a preliminary view of the company’s tax position.

2. Receiving a Tax Assessment from IRAS

After reviewing the ECI, IRAS issues a Notice of Assessment (NOA) that sets out the estimated amount of tax payable. If a company reports nil ECI, IRAS will not issue an NOA. When tax is assessed, the company must pay the amount stated in the NOA within the prescribed period.

3. Filing the Final Corporate Income Tax Return (Form C-S / C-S Lite / C)

Once the company’s accounts and tax computations are finalized, it must submit its corporate income tax return. This filing reports the company’s actual chargeable income after deducting allowable business expenses, capital allowances, and any applicable tax exemptions.

4. Reconciliation of ECI and Final Tax Return

When the final return is filed, IRAS compares it with the previously submitted ECI. If the actual chargeable income is lower than the ECI, the company will receive a refund for overpaid tax. If the actual income is higher, IRAS will issue an updated assessment, and the company will need to pay the additional tax accordingly.
Note: Readers who wish to learn about the corporate tax rates and corporate tax framework of Singapore can refer to our Singapore Corporate Tax Guide.

Financial Year vs. Year of Assessment Explained

Many business owners find it tricky to tell the difference between the Financial Year and the Year of Assessment.

Your company’s financial year (FY) is the accounting period you use to prepare your financial statements. The Year of Assessment (YA) is the year in which IRAS assesses tax on the income earned during that financial year.

For example:

  • Financial Year (FY2024): 1 January 2024 - 31 December 2024
  • Year of Assessment (YA2025): Income earned in FY2024 is assessed and finalized in YA2025.

How It Relates to Corpoarte Tax Return Filings

  • The ECI is filed within 3 months after the financial year end and reflects a preliminary estimate of the company’s taxable profits for that financial year.
  • The Income Tax Return (Form C-S / C-S Lite / C) is filed in the following calendar year (the YA) and confirms the final taxable income based on your completed financial statements and tax computation.

Examples: How Financial Year (FY) and Year of Assessment (YA) Work

Company Financial Year End (FYE)Financial Year (FY)Corresponding Year of Assessment (YA)ECI Filing DeadlineIncome Tax Return (Form C-S / C-S Lite / C) Deadline
31 December 2025FY2025YA2026By 31 March 2026 (within 3 months of FYE)By 30 November 2026
30 June 2025FY2025YA2026By 30 September 2025By 30 November 2026
31 August 2025FY2025YA2026By 30 November 2025By 30 November 2026
31 March 2026FY2026YA2027By 30 June 2026By 30 November 2027

How to File Your Estimated Chargeable Income (ECI)

All Singapore-incorporated companies must file an Estimated Chargeable Income (ECI) with IRAS within three months from the end of their financial year. The ECI is an early estimate of the company’s taxable profits for that financial year and helps IRAS plan tax assessments efficiently.

What to Report in an ECI Filing

  • Estimated revenue for the financial year (excluding gains from sale of fixed assets)
  • Estimated chargeable income, after deducting allowable business expenses, capital allowances, and any tax-exempt income
  • Tax exemption claimed, such as the Start-Up Tax Exemption or Partial Tax Exemption

Who Needs to File ECI in Singapore

Every Singapore company whether locally or foreign-owned, including Singapore branches must file its ECI with IRAS unless it qualifies for an exemption or is excluded from ECI filing.

Companies Exempt From ECI Filing

A company may be exempted from filing the ECI for a given year if it meets both of the following conditions:

  1. Its annual revenue is S$5 million or below for the financial year; and
  2. Its ECI is nil, meaning it expects no taxable income for the given financial year.

These two conditions must be satisfied simultaneously. If only one condition is met, the company must still file its ECI.

Companies are not required to seek approval from IRAS to apply this exemption. They can self-assess their eligibility based on their financial results and file accordingly.

Companies Excluded From ECI Filing

Apart from the general exemption above, certain types of entities are specifically excluded from ECI filing obligations under IRAS regulations. These include:

  • Foreign ship owners or charterers, where the local shipping agent submits a Shipping Return on their behalf.
  • Foreign universities operating in Singapore.
  • Designated unit trusts and approved CPF unit trusts.
  • Real Estate Investment Trusts (REITs) that have been granted tax treatment under Section 43(2) of the Income Tax Act 1947.
  • Entities specifically granted a waiver by IRAS in exceptional cases.
describing eci filing in singapore

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How to Calculate ECI

The Estimated Chargeable Income is the company’s estimated taxable profits for the financial year after deducting allowable business expenses, capital allowances, and other tax adjustments permitted under the Income Tax Act. To calculate ECI, follow these steps:

Step 1

Determine revenue

Include all income earned or accrued in Singapore such as sales, service income, or commissions.

Step 2

Deduct allowable expenses

Subtract business expenses that are wholly and exclusively incurred in producing income.

Step 3

Apply capital allowances

Replace accounting depreciation with capital allowances for qualifying fixed assets.

Step 4

Exclude tax-exempt or non-taxable income

Omit exempt dividends and foreign-sourced income that qualifies for exemption.

The remaining amount represents the company’s ECI for that financial year. IRAS does not require detailed computations at the time of filing, but companies should keep records to substantiate how the ECI was calculated.

When to File ECI

Every Singapore-incorporated company must file its ECI with the IRAS within three months after the Financial Year End (FYE).  IRAS typically sends a reminder near the end of the company’s financial year to file the ECI, but companies are responsible for meeting the filing deadline even if no notification is received.

Examples of ECI Filing Due Dates Based on Different Financial Year Ends

Company’s Financial Year End: 31 Mar of each year

1 Apr 2023

Basis Period for Year of Assessment (YA) 2025

31 Mar 2024

Financial Year End

30 Jun 2024

Filing Due Date for YA 2025 ECI
Company’s Financial Year End: 31 Jul of each year

1 Aug 2023

Basis Period for YA 2025

31 Jul 2024

Financial Year End

31 Oct 2024

Filing Due Date for YA 2025 ECI

How to File ECI

Companies must file their ECI electronically through the myTax Portal managed by the Inland Revenue Authority of Singapore. Paper submissions are no longer accepted.

Step 1

Log in to myTax Portal

Use your CorpPass linked to the company’s UEN.

Step 2

Select “File Estimated Chargeable Income (ECI)"

Choose the correct Year of Assessment and verify company details.

Step 3

Enter figures

Report the estimated taxable income and revenue based on management accounts or draft statements.

Step 4

Submit and receive acknowledgement

After submission, you will get an electronic receipt confirming successful filing.

Step 5

Wait for the Notice of Assessment (NOA)

If tax is payable, IRAS will issue an NOA, and payment must be made within the prescribed period.

Late Filing or Failure to File ECI

If the ECI is not filed on time, IRAS may issue an Estimated Notice of Assessment (NOA) based on the company’s past financial data or other available information. The company must pay the full tax amount stated in the NOA within one month, even if it disagrees with the estimate.

If the company disagrees with IRAS’s assessment, it can file a Notice of Objection within two months from the date of the NOA, providing its own ECI and supporting reasons for the late submission.

Companies that fail to file their ECI by the deadline may face enforcement action from the IRAS. Persistent non-compliance can lead to penalties or prosecution. General penalties may include a fine of up to S$5,000 and, in severe cases involving tax evasion, higher penalties or imprisonment.

How to File Your Form C (Tax Return)

Who Needs to File a Corporate Income Tax Return (Form C)

Every company that is incorporated in Singapore is required to file an annual Corporate Income Tax Return with the IRAS. This requirement applies to all entities, regardless of their size, ownership, or business activity. The obligation to file also applies to Singapore branches of foreign companies that derive income from Singapore sources.

Even companies that did not earn any income during the financial year must file a nil return, unless IRAS has granted a waiver (for example, for dormant companies that meet the qualifying conditions).

Understanding Form C, Form C-S, and Form C-S (Lite)

Singapore companies must submit their annual corporate income tax return using one of three forms prescribed by the IRAS: Form C, Form C-S, or Form C-S (Lite). All three forms serve the same purpose: to declare the company’s actual income, deductions, and tax payable for the relevant Year of Assessment. However, they differ in complexity and eligibility, depending on its annual revenue, the type of income earned, and whether it is claiming specific tax benefits or reliefs.

Form C

Form C is the full version of the corporate tax return. It is generally used by larger companies or those with more complex tax positions.

Companies filing Form C must attach supporting documents, including:

  • Tax computation and schedules
  • Audited or unaudited financial statements
  • Detailed profit and loss account and balance sheet

Form C is required when the company claims items such as group relief, investment allowance, foreign tax credit, or carry-back of losses.

Form C-S

Form C-S is a simplified version of the corporate tax return for smaller companies with straightforward tax affairs. Companies using Form C-S are not required to attach financial statements or tax computations, but they must keep these records for review if requested by IRAS.

To qualify for Form C-S filing, a company must:

  • Be incorporated in Singapore
  • Have annual revenue of S$5 million or below
  • Derive only income taxable at the prevailing corporate tax rate of 17% and not claim items such as group relief, investment allowance, foreign tax credit, or carry-back of losses

Form C-S (Lite)

Form C-S (Lite) is a further simplified electronic version designed for very small companies with minimal reporting requirements. It allows eligible companies to complete and submit their tax returns quickly through myTax Portal.

To file using Form C-S (Lite), a company must:

  • Meet the conditions for Form C-S filing
  • Have annual revenue of S$200,000 or below

This form requires only basic income and tax details and is suitable for companies with simple accounting records or low transaction activity.

Required Supporting Documents for Form C Filing

The documents that must accompany a company’s Corporate Income Tax Return depend on which form it files.

Companies Filing Form C Must Submit:

  • Tax computation and supporting schedules;
  • Audited or unaudited financial statements, including the directors’ report;
  • Detailed profit and loss account and balance sheet.

Companies Filing Form C-S or Form C-S (Lite) Must Retain:

  • Tax computation and schedules used to prepare the return;
  • Financial statements and management accounts;
  • Source documents such as invoices, receipts, and bank statements.
All companies must keep proper accounting and tax records for at least five years after the relevant Year of Assessment. These documents may be requested by IRAS for verification during audits or reviews.

How to File a Corporate Income Tax Return

All companies in Singapore must file their Corporate Income Tax Return electronically, paper filing is no longer accepted. Follow these steps to complete the filing process:

Step 1

Log in to myTax Portal

    Access myTax Portal using your CorpPass that is linked to your company’s Unique Entity Number (UEN).

    Step 2

    Select “File Form C / Form C-S / Form C-S (Lite)”

    Choose the correct Year of Assessment and confirm your company’s details.

    Step 3

    Prepare the required information

    Have the company’s financial statements, tax computation, and other supporting data ready before submission.

    Step 4

    Complete and submit the form

    Enter the income, deductions, and other relevant figures, review the summary, and submit the return. An acknowledgment page will appear once filing is successful.

    Step 5

    Wait for the Notice of Assessment (NOA)

    IRAS will review the filing and issue an NOA stating the amount of tax payable or refundable. The company must pay any tax due within the period specified in the notice. If a tax agent or corporate service provider handles the filing, the company must first authorize them in myTax Portal before they can file on its behalf.

    Corporate Income Tax Return Filing Deadline

    All companies must file their Corporate Income Tax Return for each YA by the deadline set by the IRAS. The current filing deadline for e-filing is 30 November of the relevant YA.

    The return filed in a given YA covers income earned during the preceding financial year. For example, income earned for the financial year ending 31 December 2025 is reported in the YA 2026 tax return.

    Penalties for Late or Non-Filing

    Failure to file the Corporate Income Tax Return, together with financial statements and tax computation, by the due date is an offence under the Income Tax Act 1947. If a company fails to file on time, the IRAS may take the following actions:
    How to File Your Corporate Income Tax Return in Singapore

    Issue an estimated Notice of Assessment (NOA)

    IRAS may raise an estimated assessment based on available data. The company must pay the estimated tax within one month, even if it disagrees with the amount.

    Issue a Section 65B(3) notice

    IRAS may require company directors to provide the information needed to complete the tax return.

    Offer to compound the offence

    A composition fee of up to S$1,000 may be imposed in place of prosecution.

    Issue a court summons

    Persistent non-compliance can result in a Notice to Attend Court for the company and its officers. Upon conviction, a fine of up to S$1,000 may be imposed, and the return must still be filed.
    Late payment penalties will also apply, and enforcement actions may be taken if payment is not made by the due date.

    Special Filing Situations

    Certain companies may have different filing requirements depending on their operational status or financial position. Below are the key scenarios and how they affect corporate tax filing obligations.

    Filing for newly incorporated companies

    Newly incorporated companies in Singapore must file both their Estimated Chargeable Income (ECI) and Income Tax Return, even if they have not started business or made a profit.

    When setting up your company, you must decide your first Financial Year End (FYE). This determines when your first tax filings are due.

    • Your first financial year can be up to 12 months or, if you choose, slightly longer (up to 18 months) to align with business or accounting needs.
    • For example, a company incorporated on 1 July 2024 may choose an FYE of 31 December 2025. So in this case,your first filing deadlines will be
      • ECI: By 31 March 2026
      • Income Tax Return (YA2026): By 30 November 2026

    Filing for dormant companies

    Dormant companies are still required to file their tax returns unless they have received a waiver from IRAS. To qualify for the waiver, the company must:

    • Have no business activities and no income during the financial year
    • Have submitted all outstanding returns up to the date business ceased
    • Not own investments that generate income (for example, shares or fixed deposits)
    • Have been deregistered for GST, if applicable
    • Not intend to recommence business within the next two years

    Once IRAS grants the waiver, the company will no longer need to file until it resumes operations.

    Filing for loss-making company

    Companies that incurred a loss during the financial year must still file their ECI and tax return. Filing ensures that the company’s losses are recorded by IRAS and can be carried forward or carried back to offset future or past taxable income, subject to the shareholding test and other qualifying conditions.

    Filing for companies with foreign income

    Companies that derive income from overseas sources must declare it in their Singapore tax return if the income is received in Singapore or deemed remitted. Certain types of foreign income, such as dividends, branch profits, or service income, may be exempt from tax under specific conditions or applicable Double Taxation Agreements (DTAs). Companies should maintain documentation to prove that the conditions for exemptions or credits are met.

    Practical Tips for Founders

    Filing corporate taxes accurately and on time is essential to maintain compliance and avoid unnecessary penalties. The following practices can help company founders and directors manage tax obligations more efficiently:

    1. Close your accounts promptly after the financial year ends: This allows enough time to prepare accurate management accounts and tax computations before the ECI deadline.
    2. Maintain complete and organized records: Keep invoices, receipts, bank statements, and contracts properly filed. IRAS requires all records to be retained for at least five years after the relevant Year of Assessment.
    3. Plan your financial year end carefully: Choose a financial year end that aligns with your business cycle and allows adequate time for accounting and audit work before filing deadlines.
    4. Monitor deadlines and file early: Set internal reminders to file the ECI within three months of FYE and the corporate tax return by 30 November of the year that followed the FYE.
    5. Work with a professional tax agent or corporate service provider: Engaging an experienced provider ensures your filings are accurate, compliant, and take advantage of available exemptions or reliefs.
    6. Review eligibility for tax incentives: Start-ups and small businesses may qualify for schemes such as the Start-Up Tax Exemption or Partial Tax Exemption, which reduces tax payable.

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    Our Corporate Tax Filing Services

    On our CSP platform, our specialists provide end-to-end support for entrepreneurs to incorporate companies and maintain full compliance with Singapore’s regulatory requirements, including tax obligations. Our experienced accounting and tax professionals assist with every stage of the corporate tax filing process, ensuring accuracy and efficiency.

    Our tax filing services include:

    • Preparing and filing Estimated Chargeable Income
    • Preparing and submitting Corporate Income Tax Returns (Form C, Form C-S, or Form C-S Lite)
    • Preparing tax computations and financial statements in accordance with IRAS requirements
    • Advising on tax exemptions, deductions, and reliefs to optimize your tax position
    • Liaising with IRAS on your behalf for assessments, clarifications, and filing waivers

    Our teams ensure your company meets all statutory deadlines and benefits from Singapore’s transparent and business-friendly tax system.

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    Eddy Putra

    Author

    Eddy Putra

    Eddy has been in the corporate services industry for over 20 years. An experienced Chartered Accountant and alumnus of Deloitte Singapore, he has extensive expertise in corporate finance, tax, structuring, and regulatory compliance. Eddy specializes in advising global clients on business expansion and corporate migration to Singapore.

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