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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallUse an accounting product listed in IRAS’ ASR+ registry that supports CIT pre-fill, tax conversion and Form C-S submission. IRAS calls the process Seamless Filing from Software (SFFS). Your software connects to IRAS through application programming interfaces (APIs), while Corppass authenticates the authorised filer. You maintain the books, map your chart of accounts to IRAS data elements, review the generated return and schedules, and submit Form C-S from the accounting system.
The connection does not transfer your filing responsibility to the software vendor. You remain responsible for choosing the correct form, checking every tax adjustment, meeting the deadline and keeping supporting records.
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What IRAS Seamless Filing from Software does
SFFS links an eligible accounting application directly to IRAS systems. Instead of re-keying figures into myTax Portal, the application converts accounting data into the format required for corporate income tax and sends the Form C-S return through an API connection. Corppass authentication is part of that linked workflow: IRAS describes APIs as intermediaries that allow two applications to communicate, with the entire filing process and authentication connected to IRAS systems.
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A typical SFFS workflow has four data stages:
- Your day-to-day transactions and year-end adjustments are maintained in the accounting application.
- The chart of accounts is mapped to IRAS-prescribed data elements, normally as a one-time setup that can be refined when your accounts change.
- The application performs tax conversion and produces a draft Form C-S, profit and loss statement, tax computation and supporting schedules.
- An authorised person reviews the draft, declares it and submits it. The software displays an acknowledgement after IRAS accepts the transmission.
SFFS is not a general-purpose electronic filing button. It is available only where the product, the company and the return type meet IRAS conditions.
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Check eligibility before connecting
Choose software in the ASR+ registry
Start with IRAS’ current ASR+ listing. Look specifically for all three corporate-income-tax capabilities: CIT pre-fill tax data, CIT tax conversion and Form C-S submission. A product that only keeps accounts, produces financial statements or exports a tax report is not necessarily SFFS-enabled.
Listing status and feature sets can change. Confirm the current entry with IRAS and the software provider before you subscribe or configure a live company file. IRAS does not endorse one commercial vendor over another; the registry confirms capability categories, not a recommendation or a guarantee that the product suits your accounts.
Confirm that your company can use Form C-S
Form C-S is the simplified corporate income tax return for a Singapore-incorporated company that meets every condition below:
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- The company derives income taxed at the prevailing 17% corporate income tax rate.
- The company is not claiming specified exclusions, including group relief, investment allowance, carry-back of current-year capital allowances or losses, or foreign tax credit or tax deducted at source.
The $5 million test is a revenue threshold, not a measure of profit. A company with low profit or a loss still has to file a return unless IRAS has granted a waiver.
Use Form C-S (Lite) only for straightforward cases
Form C-S (Lite) is available when annual revenue is $200,000 or below and the tax matters are straightforward. It contains six essential fields, compared with 18 fields in Form C-S. The lower field count does not remove the need to keep complete accounts or check the underlying tax treatment.
Know when Form C is required
If the company falls outside the Form C-S conditions, it must file Form C. Form C filers submit financial statements, a tax computation and supporting documents in addition to the return. Some accounting products that support SFFS Form C-S do not support Form C submission, so check this capability before relying on an application for the whole filing.
What you need before setup
Prepare the following items before opening the software’s tax-filing module:
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- A completed accounting file for the relevant financial year, including bank reconciliations and year-end journals.
- The company’s legal name, Unique Entity Number (UEN) or Entity ID and financial-year information.
- Access to the ASR+ product and the vendor’s implementation instructions.
- A person who can approve Corporate Income Tax filing in Corppass.
- Supporting records for revenue, expenses, fixed assets, financing, payroll and unusual transactions so that tax adjustments can be explained.
- A review plan: one person prepares the data and, where practical, another authorised person checks the return before submission.
Do not start with a partially maintained ledger and expect tax conversion to repair it. Pre-fill can only use the transactions and classifications present in the accounting file.
Step-by-step: connect the accounting system to IRAS
1. Select an eligible product and edition
Use the ASR+ listing to identify products with CIT pre-fill, tax conversion and Form C-S submission. Ask the provider whether those features apply to your edition, Singapore entity type and intended Year of Assessment (YA). Confirm whether the product supports multiple companies, consolidated groups, foreign-currency ledgers and the specific schedules your company may need.
Get written implementation instructions from the provider. Default mappings and tax codes differ between products, so a demonstration or generic accounting tutorial is not a substitute for the provider’s SFFS setup guide.
2. Complete the books for the relevant period
Record all operating transactions before connecting the tax workflow. Reconcile bank and credit-card accounts, post depreciation and accruals, clear suspense balances and document material estimates. Check that revenue is not netted incorrectly against expenses and that owner, director and related-party transactions are classified consistently.
Keep source documents in the accounting system or an organised repository. The SFFS return is generated from accounting data, but IRAS can request the underlying records later.
3. Map the chart of accounts once
Open the product’s tax-mapping or SFFS configuration area and map each relevant ledger account to the IRAS-prescribed data elements. Some products supply default mappings; review every default rather than accepting it automatically. An account called “repairs” could contain capital improvements, and “other income” could combine items with different tax treatments.
For each mapping, ask:
- Does the account belong in the profit and loss statement or balance sheet?
- Is the amount revenue, an expense, a capital item, a deduction, an allowance or a non-taxable item?
- Will the amount require a tax adjustment in the computation?
- Should a sub-account be split so the return can present the required detail?
Record who approved the mapping and the date. Revisit it when you add accounts, change your business model or adopt a new tax treatment. A one-time mapping reduces repetitive work, but it is not a permanent guarantee that future transactions are classified correctly.
4. Configure Corppass authority
The responsible person must have the Corppass Approver role for Corporate Income Tax filing. In the Corppass administration, grant the appropriate Corporate Income Tax filing authority to the user who will declare the return. Confirm the user’s identity details and company association before attempting a live submission.
Separate preparation from approval where your internal controls require it. A bookkeeper may prepare and review the draft, while the authorised Approver performs the declaration and final submission. If the authorised person changes, update Corppass before the deadline; do not share Singpass or Corppass credentials.
5. Link the company and start the tax return
In the accounting application, open the corporate tax or SFFS filing function, select the company and the relevant YA, and follow the connection prompts. The exact labels differ by product. The process should direct you to Corppass authentication rather than asking you to type a password into an unfamiliar third-party form.
Check the company name, UEN or Entity ID, basis period and return type shown after authentication. A wrong entity or YA can produce a technically valid submission for the wrong period, which is much harder to correct than a rejected connection.
6. Generate and review the draft documents
Run the software’s pre-fill and tax-conversion process. It should generate a draft Form C-S together with a profit and loss statement, tax computation and supporting schedules. Treat every figure as a proposal for review, not as an automatic assessment by IRAS.
Use a documented review sequence:
- Compare total revenue and major expense categories with the final trial balance and financial statements.
- Investigate unmapped accounts, “other” categories, negative balances and unexpected zeroes.
- Check tax adjustments, including disallowable expenses, capital allowances, income not subject to tax and timing differences.
- Verify claims and exclusions. If the company is using group relief, investment allowance, carry-back relief or foreign tax credit or tax deducted at source, reassess whether Form C-S is permitted.
- Confirm the six-field Form C-S (Lite) route is not being used when the company needs the fuller Form C or Form C-S treatment.
- Have the authorised reviewer compare the generated schedules with the retained source documents and resolve exceptions with the provider or tax adviser.
7. Declare, submit and save the acknowledgement
After review, the Corppass Approver declares the return and submits Form C-S from the software. Save the acknowledgement displayed by the application, including the submission date, YA, company identifier and any reference number. Also retain the submitted return and the final profit and loss statement, tax computation and supporting schedules.
SFFS submission is limited to Form C-S. If the company must file Form C, follow the applicable IRAS filing route and provide the required financial statements, tax computation and supporting documents.
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Form C-S, Form C-S (Lite) or Form C? Use this decision table
| Return | When it applies | Information and documents |
|---|---|---|
| Form C-S (Lite) | Annual revenue of $200,000 or below and straightforward tax matters | Six essential fields; keep complete accounting records and supporting evidence |
| Form C-S | Singapore-incorporated company with annual revenue of $5 million or below, income taxed at the prevailing 17% rate, and none of the specified exclusions | 18-field simplified return plus the generated profit and loss statement, tax computation and schedules for review and retention |
| Form C | Any company outside the Form C-S conditions | Form C, financial statements, tax computation and supporting documents |
These thresholds and conditions apply to the relevant YA and should be checked against the current IRAS Form C-S overview. Revenue alone does not decide the form; the exclusions and nature of the tax claims matter as well.
Deadlines and the SFFS extension
The annual statutory deadline for Form C-S (Lite), Form C-S and Form C is 30 November. For SFFS Form C-S returns for YA 2023 through YA 2027, IRAS automatically gives a 15-day extension, moving the deadline to 15 December. No separate extension request is needed for that SFFS concession.
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| Situation | Deadline | Important qualification |
|---|---|---|
| Form C-S (Lite), Form C-S or Form C under the ordinary annual rule | 30 November | Applies unless a specific IRAS concession or arrangement changes the date |
| SFFS Form C-S for YA 2023–YA 2027 | 15 December | Automatic 15-day extension; no separate request |
Build an internal deadline earlier than the IRAS date. Allow time to repair unmapped accounts, correct Corppass permissions, obtain missing invoices and investigate a rejected or incomplete transmission. The extension applies to qualifying SFFS Form C-S submissions; do not assume it changes the deadline for a Form C filing or another filing route.
myTax Portal, Corppass and SFFS: what changes?
You still need a valid corporate identity and authorised person even when filing from software. In the myTax Portal route, the filer needs Corppass Approver authorisation for Corporate Tax (Filing and Applications), Singpass and the company UEN or Entity ID. SFFS moves the data-transfer and filing screens into the accounting application, but the authorisation principle remains: an authorised person authenticates and declares on behalf of the company.
Use myTax Portal when the company must file a return that the SFFS product does not support, when the software connection is unavailable, or when IRAS specifically directs you to another route. Do not submit the same YA through both channels. Check the acknowledgement and your internal filing log before attempting a second transmission.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to compare accounting products for SFFS
Price and general bookkeeping features do not tell you whether a product will reduce filing risk. Compare these capabilities directly with the vendor and the current ASR+ entry:
| Comparison point | Questions to ask |
|---|---|
| ASR+ status | Is the exact product and edition currently listed for SFFS? |
| CIT functions | Are CIT pre-fill, tax conversion and Form C-S submission all included, or are they separate add-ons? |
| Account mapping | Are default mappings supplied? Can you override them, split accounts and see unmapped items? |
| Corppass and API workflow | Does the product provide an in-application Corppass authentication flow and clear error messages? |
| Review controls | Can users see the generated return, tax computation, schedules and changes before approval? |
| Acknowledgement and audit trail | Can you download the acknowledgement, submitted values, mapping history and user activity? |
| Form coverage | Does it support only Form C-S, or also the company’s required Form C process? |
| Vendor assistance | Are setup instructions, Singapore tax support and escalation contacts available during filing season? |
Ask for a trial using a copy of your chart of accounts, not a generic demonstration company. A product that handles your unusual revenue streams, foreign-currency balances or capital-allowance data is more useful than one with a polished but limited demo.
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Records you must retain after filing
Connecting software does not remove statutory record-keeping duties. Companies generally must retain records, source documents, accounting records, schedules and bank statements for at least five years from the relevant YA. Keep the final ledger, mapping configuration, tax adjustments, invoices and receipts, bank reconciliations, depreciation or capital-allowance workings, submitted return and acknowledgement together.
Use a retention process that survives staff turnover. Export documents in a readable format, restrict editing of the filed copy and record who approved the submission. If the accounting subscription is cancelled, make sure you can still retrieve the records and schedules required for the five-year period.
Common connection and filing problems
The product cannot be found in the ASR+ listing
Do not assume that an ordinary cloud accounting product is SFFS-capable. Check the exact product name and edition, then ask the provider whether the listing is current. If the product lacks the required CIT pre-fill, conversion and Form C-S submission features, use another eligible product or file through the applicable IRAS route.
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Corppass authentication fails
Verify that the user has the Corporate Income Tax filing Approver role, is linked to the correct company and is using the intended Singpass identity. An administrator may need to update the authorisation before retrying. Never work around a failed permission check by sharing credentials.
Accounts remain unmapped or the tax conversion looks wrong
Return to the chart-of-accounts mapping, identify the source ledger account and inspect the transactions behind its balance. Split a mixed account where necessary, correct the accounting classification and regenerate the draft. Keep a note of material mapping changes so the reviewer can understand why the tax computation changed.
The generated return does not match the financial statements
Stop before declaration. Compare the trial balance, profit and loss statement and generated tax schedules line by line. Look for late journals, unreconciled bank items, duplicated imports, foreign-exchange adjustments and accounts excluded from the mapping. Regenerate only after the accounting file is corrected.
The company is outside Form C-S conditions
Do not force the simplified workflow. If an exclusion applies or the revenue and tax conditions are not met, determine whether Form C is required and prepare the financial statements, tax computation and supporting documents that accompany it. Obtain professional advice when the form choice or tax treatment is uncertain.
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Check the software’s filing history, notification area and exported documents before submitting again. Confirm whether IRAS accepted, rejected or is still processing the transmission. Contact the product provider or IRAS through the prescribed support channel with the company identifier and submission details; retain screenshots or error references.
Responsibilities that remain with the company
- File every required annual return, including a nil or loss return, unless IRAS granted a waiver.
- Choose the correct form and confirm that the company satisfies every Form C-S or Form C-S (Lite) condition.
- Maintain complete and accurate accounting records and supporting documents.
- Review mappings, tax adjustments and generated schedules before declaration.
- Keep Corppass authority current and protect Singpass credentials.
- Meet the applicable deadline and retain evidence of submission for at least the required record-retention period.
Software automates data transfer and formatting; it cannot decide whether an expense is deductible, whether a relief claim is available or whether a company qualifies for a simplified return.
Quick Recap
A practical annual SFFS checklist
- Confirm the product remains ASR+ listed with all three required CIT capabilities.
- Close the accounting period and reconcile the books.
- Review new or changed ledger accounts and update their IRAS mappings.
- Confirm the company’s revenue, tax rate and exclusion status for the relevant YA.
- Check Corppass Approver authority for Corporate Income Tax filing.
- Generate the draft return, profit and loss statement, tax computation and schedules.
- Investigate every unmapped account, unusual balance and material tax adjustment.
- Obtain reviewer approval and submit Form C-S through the software.
- Save the acknowledgement and filed documents in the company’s tax archive.
- Retain source records, accounting data and schedules for at least five years from the relevant YA.
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