Form C-S (Lite) Filing Without an Accountant: The 30 November 2026 Corporate Tax Deadline

If your Singapore company's financial year ended at any point in 2025, your Year of Assessment 2026 corporate income tax return is due on 30 November 2026. If your revenue for that year was $200,000 or less and you meet the Form C-S conditions, you can file it yourself using Form C-S (Lite) — six essential fields, e-filed through myTax Portal, no accountant on staff required. The form itself takes under an hour. What takes the time is the eight weeks before it: closing your FY2025 accounts, reconciling a tax computation against them, and getting your supporting documents into a state you could actually hand over if IRAS asks. That work starts in early October, not mid-November.

What exactly is due on 30 November 2026?

One return, e-filed. Paper filing was discontinued years ago, so everything goes through myTax Portal with a Corppass login that has been assigned the corporate tax role. If nobody in your company has ever logged in — or the only person who had access has left — fix that first. Corppass access recovery is not a same-week process, and it is the single most common reason an otherwise-ready SME misses the date.

Note which year you are filing. YA 2026 covers the financial year that ended in 2025. A company with a 31 December year-end is filing FY2025 numbers. A company with a 30 June year-end is filing the year to 30 June 2025. Owners routinely pull the wrong year's trial balance, then spend a week trying to reconcile a figure that was never going to reconcile.

Separately from this: Estimated Chargeable Income (ECI) is due within three months of your financial year end, unless you qualify for the waiver — broadly, revenue not exceeding $5 million and nil ECI. The 30 November return is not a substitute for ECI, and filing one does not close out a missed other.

Does your company qualify for Form C-S (Lite), Form C-S, or Form C?

The three forms are a ladder, and where you sit determines how much work November holds.

• Form C-S (Lite) — annual revenue of $200,000 or less, and you meet all the Form C-S conditions. Six essential fields.
• Form C-S — annual revenue of $5 million or less, incorporated in Singapore, income taxable only at the prevailing 17% rate, and you are not claiming carry-back of capital allowances or losses, group relief, investment allowance, foreign tax credit, or tax deducted at source.
• Form C — everything else. Financial statements and a tax computation are submitted with the return.

A point owners miss: with Form C-S and C-S (Lite) you do not submit financial statements and a tax computation, but you are still required to have prepared them and to keep them. The simplified form reduces what you upload. It does not reduce what you must be able to produce.

What documents do you need before you open myTax Portal?

Build this pack in October, while the numbers are still fresh and the people who know them are still at their desks. December leave season is a bad time to be asking what a $14,000 payment in March was for.

• Closed FY2025 trial balance, profit and loss, and balance sheet
• Bank statements for the full financial year, reconciled to the ledger
• Sales listing tying revenue in the accounts to revenue you will declare
• Supplier invoices and receipts for claimed expenses — the actual documents, not just ledger lines
• Fixed asset register with purchase dates and amounts, for capital allowances
• Director's fees and remuneration records, and CPF filings
• Prior year's Notice of Assessment and tax computation

IRAS generally requires business records to be kept for five years. If yours live in a mix of email attachments, a WhatsApp thread, and one shoebox, that is the infrastructure problem to solve now — not the filing.

Which numbers in your accounts are not tax numbers?

Accounting profit is not chargeable income, and this is where self-filers make errors that surface a year later as an amended assessment. Common adjustments for a small company:

• Non-deductible expenses added back — fines and penalties, private car expenses on S-plate cars, private or domestic spending run through the company, and medical expenses above the statutory cap on total remuneration
• Depreciation added back, and capital allowances claimed in its place under the Income Tax Act's capital allowance provisions
• Renovation and refurbishment costs, which follow their own deduction rules and cap rather than being ordinary repairs
• Exemptions — the Start-Up Tax Exemption if you are within your first three YAs and qualify, otherwise Partial Tax Exemption

On rebates: do not assume last year's corporate income tax rebate carries forward. Rebates are announced Budget by Budget and the amount, cap and any cash grant floor change. Check what has actually been legislated for YA 2026 on the IRAS site rather than copying the figure from your prior year computation.

What does a no-accountant filing sequence look like?

Work backwards from 30 November and give yourself a buffer that absorbs one bad week.

• Early October — confirm Corppass access works. Confirm which financial year you are filing. Confirm which form you qualify for.
• Mid-October — close FY2025 properly: bank reconciliations, accruals, unbilled revenue, stock. Chase the missing receipts now.
• Late October — prepare the tax computation. Add backs, capital allowances, exemptions. Save it as a working file you can re-open next year.
• Early November — have a second pair of eyes check the computation. A part-time accountant reviewing a finished computation costs a fraction of one preparing it from scratch.
• Mid-November — file. Do not aim for the 30th. The portal is busiest in the final week and you want room to fix a rejection.

What happens if you miss 30 November?

IRAS may issue an estimated Notice of Assessment based on its own view of your income — which is usually higher than your actual position, and which you must pay even while objecting. Late filing can also attract a composition fee, and continued non-filing can lead to a summons against the company and its directors. The penalty is not the real cost, though. The real cost is that an estimated assessment forces you into a dispute you will fund out of Q1 cash flow, in the same quarter you were planning to spend on systems.

Frequently asked questions

Can I file Form C-S (Lite) if my company made a loss?
Yes, provided you meet the revenue and other Form C-S conditions. A loss year still requires a return, and filing it is how unabsorbed losses get properly recorded for carry-forward. Skipping the filing because there is no tax to pay is how companies lose relief they were entitled to.

My company was dormant all year — do I still need to file?
Yes, unless IRAS has granted a waiver of the requirement to file. A dormant company files the simplified return for dormant companies. Apply for the waiver if you expect to stay dormant; do not simply stop filing and hope the notices stop too.

Do I still need an accountant if I file myself?
For the return, often not. For the accounts underneath it, usually yes — at review level rather than preparation level. The sustainable split for a small Singapore company is clean bookkeeping maintained in-house throughout the year, with a qualified reviewer checking the year-end computation before submission.

The filing on 30 November is the easy part. What determines whether it is easy is whether your company can produce twelve months of supporting documents on demand — and that is a systems question you answer in October, not a tax question you answer in November.