Singapore companies file their annual Corporate Income Tax Return online through IRAS’s myTax Portal. The practical sequence is: authorize an employee or tax agent in Corppass, sign in with Singpass and the company’s UEN or Entity ID, select Form C-S (Lite), Form C-S or Form C, attach or retain the required records, submit the declaration, and save the acknowledgement.
The annual return is separate from Estimated Chargeable Income (ECI). ECI is generally due within three months after the financial year end, while the Form C-S/Form C-S (Lite)/Form C return has its own annual deadline. Choosing the wrong form, missing the authorization step or filing late can lead to enforcement action.
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What you need before opening myTax Portal
Online filing is available at mytax.iras.gov.sg. Access is controlled through Corppass, so the person who completes the return must have the right company role before attempting to file.
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- Corppass authorization: an employee or tax agent must be appointed as an Approver for the “Corporate Tax (Filing and Applications)” e-service.
- Personal login: the authorised filer uses Singpass.
- Entity identifier: keep the company’s Unique Entity Number (UEN) or Entity ID available.
- Accounting records: have the financial statements, tax computation and supporting schedules ready before starting.
- Correct Year of Assessment: confirm which financial year the return covers and whether any ECI filing has already been made for that financial year.
If an accountant or other tax professional will file, complete the Corppass appointment first. Giving someone access to accounting records does not, by itself, give that person authority to submit an IRAS return.
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Choose the right corporate tax return
IRAS provides three annual return formats. Revenue is an important screening test, but it is not the only one. A company must satisfy all conditions for the simplified form it intends to use; otherwise it files Form C.
| Return | Who may use it | What is submitted or retained | Preparation implication |
|---|---|---|---|
| Form C-S (Lite) | Companies with annual revenue of $200,000 or below, provided the other IRAS conditions are met. | A shorter set of tax particulars. Keep the financial statements and tax computation for IRAS if requested. | IRAS says a direct electronic submission usually takes at least 10 minutes. |
| Form C-S | Qualifying Singapore-incorporated companies with annual revenue of $5 million or below, income taxed at the prevailing 17% rate, and the other Form C-S conditions. | Retain the financial statements and tax computation; provide them to IRAS if requested. | Usually quicker than Form C because the return is simplified, but eligibility must be checked carefully. |
| Form C | Companies that do not satisfy the conditions for Form C-S (Lite) or Form C-S. | Upload the financial statements, detailed profit-and-loss statement, tax computation and supporting documents as clear PDF files. | IRAS says a direct electronic submission usually takes at least 30 minutes, excluding time needed to prepare attachments. |
When Form C-S (Lite) is appropriate
Form C-S (Lite) is intended for the smallest qualifying companies. The revenue test is annual revenue of $200,000 or below for the relevant basis period. Do not select it solely because the company is dormant, has no tax payable or has few transactions; the remaining IRAS requirements still apply.
When Form C-S is appropriate
Form C-S is available to qualifying Singapore-incorporated companies with annual revenue of $5 million or below whose income is taxed at the prevailing 17% rate, together with the other conditions set by IRAS. A company that fails any condition must use Form C, even if its revenue is under the stated ceiling.
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When Form C is required
Use Form C when the company is outside the simplified-form criteria. Form C requires a fuller disclosure and electronic attachment package. If eligibility is uncertain, review the current IRAS conditions or ask the company’s tax agent before submitting; filing a shorter form that the company is not entitled to use can create a compliance problem.
Know both tax deadlines
The annual return and ECI are different filings with different purposes.
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| Filing | Purpose | Normal timing | Important qualification |
|---|---|---|---|
| ECI | An estimate of the company’s chargeable income and tax for the financial year. | Generally within three months after the financial year end. | It is not the final Corporate Income Tax Return. Exact dates depend on the company’s financial year end. |
| Form C-S (Lite), Form C-S or Form C | The annual Corporate Income Tax Return supported by the company’s accounts and tax computation. | 30 November every year. | IRAS states that failure to file can trigger enforcement measures. |
| Qualifying SFFS Form C-S filing | A Form C-S submission made through qualifying accounting software under the Simplified Filing Software (SFFS) arrangement. | For YA 2023 through YA 2027, IRAS automatically extends the 30 November deadline by 15 days, to 15 December. | The extension applies only when the software and filing meet the SFFS requirements; it does not apply automatically to every electronic submission. |
Check the live IRAS calendar for the relevant Year of Assessment and financial year end, particularly if the company changes its accounting year or is using SFFS software. Treat the annual return deadline as a separate compliance date even when ECI has already been filed.
Step-by-step: file directly in myTax Portal
- Confirm the authorised filer. In Corppass, appoint the employee or tax agent as an Approver for “Corporate Tax (Filing and Applications).” If a third party will prepare the return but a company officer must approve it, make sure the approval workflow is assigned to the right people.
- Assemble the login details. The filer should have a working Singpass account and the company’s UEN or Entity ID. Resolve Corppass or Singpass access problems before the filing session rather than leaving them until the deadline day.
- Open the portal. Go to mytax.iras.gov.sg, choose the corporate tax filing service, and sign in using the authorised individual’s credentials.
- Identify the outstanding return. Select the company and the relevant Year of Assessment. Check that the financial year covered by the return is correct; do not use an old draft or a different entity’s record.
- Select the form. Choose Form C-S (Lite), Form C-S or Form C based on all eligibility conditions, not revenue alone. If the company does not meet a simplified-form requirement, switch to Form C before entering figures.
- Enter the tax information. Transcribe figures from the approved financial statements and tax computation. Reconcile accounting profit to chargeable income, and make sure adjustments, exemptions and claims are supported by the company’s working papers.
- Attach documents when Form C requires them. Upload the financial statements, detailed profit-and-loss statement, tax computation and supporting documents as readable PDFs. Check that each file belongs to the selected company and Year of Assessment.
- Review and declare. Use the portal’s review screen to check amounts, contact details, form selection and attachments. Read the declaration, then submit only after the authorised person is satisfied that the return is complete and accurate.
- Save proof of filing. Download or print the electronic acknowledgement and store it with the signed accounts, tax computation, uploaded PDFs and Corppass authorization record.
Prepare records and PDF attachments correctly
Records for every company
Prepare the final financial statements and tax computation before opening the return. The tax computation should explain the adjustments from accounting profit to chargeable income and tie to the figures entered in the return. Keep source schedules, invoices and other evidence under the company’s normal record-retention process so that the submitted figures can be reproduced if IRAS asks questions.
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Form C filers must attach the financial statements, detailed profit-and-loss statement, tax computation and supporting documents. IRAS advises using clear PDFs, at least 11-point type where documents are reduced, and 100 dpi black-and-white scans when reducing attachment size. Compression should not make figures, notes or signatures unreadable.
What Form C-S filers retain
Form C-S and Form C-S (Lite) filers generally do not upload the full accounts with the simplified return. They must retain the financial statements and tax computation and provide them to IRAS if requested. Retaining only the portal acknowledgement is therefore insufficient.
Alternative filing routes
Qualifying accounting software (SFFS)
Eligible Form C-S filers can submit through qualifying accounting software under IRAS’s SFFS arrangement. The software transfers the required data to IRAS, which can reduce re-keying between the accounts and the return. The 15-day extension described above is tied to qualifying SFFS submissions for YA 2023–YA 2027, not to every product that advertises tax filing.
Before relying on the route, confirm that the company qualifies for Form C-S, that the software is on the qualifying SFFS list for the relevant Year of Assessment, and that the submission has actually been transmitted and acknowledged. Keep the software-generated confirmation with the company’s records.
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A company may authorize a tax agent or another third party through Corppass. The agent can prepare and submit the return, but the company remains responsible for providing complete records, approving the tax position and meeting its statutory obligations. Agree in writing who will calculate the tax, who will approve the declaration, who will monitor notices and who will retain the acknowledgement.
IRAS does not identify a particular provider in the guidance used here. Fees, turnaround times and software arrangements are therefore matters to confirm directly with the chosen agent; no universal price or service level applies.
Compare the available filing methods
| Factor | Direct myTax Portal | SFFS accounting software | Tax agent or other third party |
|---|---|---|---|
| Eligibility | Available to companies filing the applicable return after Corppass authorization. | Generally for eligible Form C-S filers using qualifying software. | Any company may appoint an authorised third party, subject to the agent’s acceptance and the company’s authorization. |
| Preparation time | IRAS estimates at least 10 minutes for Form C-S/Form C-S (Lite) and at least 30 minutes for Form C, not including accounting work. | Varies with the software and the quality of the underlying accounts. | Depends on the agent’s workload and how complete the records are. |
| Attachments | Form C requires PDFs; simplified-form filers retain records for possible request. | Data and any required documents follow the software’s SFFS workflow. | The agent may collect documents through its own system, but the statutory record requirements remain. |
| Authorization | Company employee must be a Corppass Approver for the corporate tax service. | Company must authorize the software connection and the submitting user as required by Corppass. | Company must appoint the agent or third party through Corppass. |
| Software or service cost | No separate IRAS filing fee is stated in the guidance. | Any subscription or implementation cost depends on the software; no standard amount is stated. | Professional fees depend on the engagement; no standard amount is stated. |
| Deadline treatment | Use the normal annual deadline. | Qualifying SFFS Form C-S submissions receive the stated YA 2023–YA 2027 extension. | The company must ensure the agent submits by the deadline that applies to its filing route. |
After submission: acknowledgement and status checks
Save the acknowledgement immediately. It is the evidence that the portal accepted the submission, not merely that a draft was opened. Keep a copy outside the portal in case a user’s access changes.
IRAS says filing status can be checked in myTax Portal or through the IRAS Bot from three working days after filing. If the status is not visible sooner, retain the acknowledgement and allow that processing period before treating the submission as missing.
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Monitor the company’s registered contact channels for follow-up requests. If IRAS asks for the accounts or tax computation from a Form C-S filing, provide the retained records that support the submitted figures.
What happens when a return is late
IRAS may issue an estimated Notice of Assessment that is payable within one month. It may also offer composition, issue a Section 65B(3) notice to a director or issue a court summons. These are separate consequences from any tax eventually assessed, so waiting for IRAS to contact the company is not a substitute for filing.
Overdue returns are filed through myTax Portal after the required Corppass authorization is in place. Gather the missing accounts and tax computation, correct the access problem if necessary, and submit the outstanding return as soon as possible. Keep evidence of the late submission and any correspondence about the reason for delay.
Dormant companies
A dormant company still has to e-file the dormant-company form unless IRAS has granted a waiver. Dormancy does not automatically remove the filing obligation. Check whether a waiver exists before assuming that no online action is required.
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Common problems and practical fixes
The filer cannot see the company
Check that the person is linked to the correct UEN or Entity ID in Corppass and has the Approver role for the exact “Corporate Tax (Filing and Applications)” service. A Singpass login without the entity authorization will not display the company’s return.
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The company is unsure which form to select
Start with the full Form C-S (Lite) and Form C-S conditions, including the revenue ceilings and the 17% tax-rate condition for Form C-S. If any condition is not met or cannot be evidenced, use Form C and prepare the full attachment set.
PDF files are rejected or unreadable
Open every PDF before uploading, confirm that pages are upright and complete, and reduce scan resolution only as far as readability permits. The IRAS guidance points to at least 11-point text and 100 dpi black-and-white scans when reducing file size; do not remove notes or schedules simply to make a file smaller.
ECI was filed but the annual return remains outstanding
ECI is an estimate and does not replace Form C-S (Lite), Form C-S or Form C. Return to the annual corporate tax filing service and complete the outstanding return for the relevant Year of Assessment.
An agent says the return was submitted but no status appears
Ask for the portal acknowledgement or software transmission confirmation, verify the entity and Year of Assessment, and check again after the three-working-day status period. If no evidence exists, the company’s authorised user should investigate through myTax Portal rather than relying on an email assertion.
A filing-day checklist
- Confirm the company’s financial year end and Year of Assessment.
- Confirm the annual-return deadline and any applicable SFFS extension.
- Check Corppass authorization for the person who will submit or approve.
- Have Singpass and the UEN or Entity ID ready.
- Decide eligibility for Form C-S (Lite), Form C-S or Form C using all conditions.
- Reconcile the financial statements to the tax computation and return figures.
- Prepare Form C PDFs, or store the records required for a simplified return.
- Review the declaration and attachments before submission.
- Save the acknowledgement and retain the source records.
- Check filing status through myTax Portal or the IRAS Bot after the stated processing period.
Three examples of choosing a route
Small qualifying company filing directly
A Singapore company whose annual revenue falls within the Form C-S (Lite) ceiling and that meets the remaining conditions can use the shortest return. Its director authorizes an employee as an Approver, the employee signs in with Singpass, enters the figures from the tax computation and retains the accounts and computation after submission.
Growing company still within Form C-S limits
A Singapore-incorporated company below the Form C-S revenue ceiling may use Form C-S only if its income is taxed at the prevailing 17% rate and the other conditions are satisfied. If it uses qualifying SFFS software, it should verify the software’s eligibility and the special filing-date treatment before relying on the extension.
Company outside simplified-form criteria
A company that fails a Form C-S condition files Form C. It should allow time to prepare the detailed profit-and-loss statement, tax computation and supporting PDFs, then have the authorised Approver review the declaration and attachments before submitting.
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Successful online filing is mainly a control process: authorize the right person in Corppass, match the company to the correct return, separate ECI from the annual return, prepare evidence before entering figures, and preserve the acknowledgement. Direct myTax Portal filing is the standard route; qualifying SFFS software may provide a limited extension, and a tax agent can submit when properly authorised. Late filing can produce an estimated assessment, composition, a director notice or a summons, so resolve access and form-selection issues before the applicable deadline.
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