Preview guide — review before live publication

Corporation tax deadlines directors should not leave until year-end.

Corporation tax planning is easier when directors separate the payment date, tax return filing, Companies House accounts and the practical record work that has to happen first.

Quick answer: for many UK companies, corporation tax is normally payable nine months and one day after the accounting period ends, while the company tax return is usually due 12 months after the period end. Accounts filing deadlines can be different. Always confirm the actual dates for the company before relying on them.

The four dates directors often blur together

Limited company deadlines can feel like one large year-end event, but they are not one job. A director usually needs to think about the accounting period end, corporation tax payment date, company tax return deadline and Companies House accounts filing deadline separately.

Deadline area
Why it matters
Director action
Company year-end
The cut-off point for income, costs, payroll, dividends and director transactions in that accounting period.
Review records before this date where possible.
Corporation tax payment
Cash needs to be available before filing is necessarily complete.
Estimate early and protect cashflow.
Company tax return
The CT600 and computations explain the tax position to HMRC.
Answer accountant queries before the deadline becomes urgent.
Companies House accounts
Accounts filing has its own deadline and public-record implications.
Keep statutory accounts preparation moving alongside tax work.

What to prepare before corporation tax work starts

The fastest year-end work normally comes from clean source records, not from last-minute chasing. Directors should try to prepare evidence and explanations before the accountant starts calculating tax.

  • Bank accounts reconciled against sales, purchases, wages and transfers.
  • Sales invoices and unpaid customer balances reviewed.
  • Supplier invoices, receipts and card payments organised.
  • Payroll, pension and PAYE records checked against the accounts period.
  • VAT returns and any CIS records reconciled where relevant.
  • Director loan account movements explained, including personal spending from company funds.
  • Dividend paperwork and available profit position checked before dividends are treated as routine.
  • Large equipment, software, finance, vehicle or one-off costs flagged for tax treatment.

Common mistakes that create deadline pressure

Most corporation tax deadline problems are not caused by the tax calculation alone. They come from unclear records, unsupported director payments, missing evidence or discovering too late that cash has not been set aside.

Waiting until accounts are due

If records are only reviewed near the filing date, useful year-end planning points may already have passed.

Confusing payment and filing

Corporation tax may need paying before the final filing deadline, so directors should not wait for the last statutory date to think about cash.

Assuming every cost is allowable

Capital items, mixed-use costs, personal spending and poorly evidenced expenses need careful treatment.

Ignoring director loans

Unexplained withdrawals can affect tax, dividends and accounts presentation. They should be reviewed early.

How Gardian can help directors stay ahead

Gardian’s role is to turn year-end from a scramble into a controlled review: records, director payments, corporation tax estimates, Companies House dates and next-year improvements all in one calmer process.

For a company with messy records or unclear director drawings, the right first step is usually a structured review rather than a quick tax-saving promise.

Important: this guide is general information for preview review. Corporation tax deadlines, filing duties and tax treatment depend on company circumstances and current HMRC/Companies House rules.
Corporation tax deadline FAQs

Questions directors ask when year-end gets close.

When is corporation tax normally due?

For many UK companies, corporation tax is normally due nine months and one day after the accounting period ends. Some companies or situations can have different rules, so confirm the actual date.

Is the tax deadline the same as accounts filing?

No. Payment, company tax return filing and Companies House accounts deadlines are related but different. Treating them as one date can create cashflow and filing pressure.

What should I send my accountant?

Clean bank records, invoices, receipts, payroll, VAT records, dividend paperwork, director loan explanations and notes for unusual transactions are a strong starting point.

Next step

Want year-end to feel less reactive?

Use the Tax Review Check to confirm fit, deadlines and records before choosing the right Gardian support route.

Start with fit and deadlines

A short qualification-first process helps identify whether Gardian can help with corporation tax, records and director planning.

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