Corporation Tax Accountants

What does a corporation tax accountant do?

They turn your accounts into a tax computation, file the CT600, and tell you what to pay and when. Capital allowances, disallowable expenses and reliefs mean the tax bill is not a copy of the profit and loss. They also keep Companies House and HMRC dates from colliding.

Most directors buy this as part of a limited-company package, not as a standalone CT600. R&D claims, associated companies and capital-allowance pools sit outside a vanilla return. If a listing has no published fee we show that honestly rather than inventing a cell.

When is corporation tax due in the UK?

Payment is due nine months and one day after the accounting period ends for most companies. The CT600 return is due within 12 months. Those are different dates — missing the payment date costs interest even if the return is still open. Large companies pay in quarterly instalments instead.

HMRC has said it does not intend to introduce Making Tax Digital for Corporation Tax. Companies keep filing the CT600 as now. Confirm current rules on GOV.UK — our dates are from the 17 July 2026 review.

How much does a corporation tax accountant cost?

Corporation tax is usually inside a limited-company package at £83–£227 per month on our editorial benchmarks, covering accounts and the CT600. A standalone company tax return is commonly a fixed annual fee — confirm scope before you treat the monthly number as the whole bill.

Advisory work on associated companies, group relief or a sale is extra. Compare three written quotes that name whether accounts are included. Do not compare a CT600-only price with a full monthly package.

Can I file my own CT600?

You can, but the computation must follow tax rules that differ from your accounts. Most directors use an accountant because a missed relief or a late payment costs more than the fee. Dormant companies with no tax to pay still have filings — get those dates right.

HMRC software and commercial packages exist. They still need someone who knows what a disallowable expense is. If you have a director's loan, capital allowances, or R&D, DIY is rarely cheaper.

Is Making Tax Digital coming for corporation tax?

No. HMRC confirmed in its July 2025 Transformation Roadmap that it does not intend to introduce Making Tax Digital for Corporation Tax. Companies keep filing CT600 returns as they do today.

Do not pay extra for a “company MTD” product that does not exist. VAT-registered companies still need MTD-ready software for VAT. Sole traders and landlords have a separate Income Tax MTD timetable.

What is usually included with corporation tax support?

The computation, the CT600, and a payment reminder. Accounts to Companies House are usually the same engagement. Personal Self Assessment for dividends is often extra. R&D is a different claim.

Ask whether HMRC correspondence is included. A compliance check is not a monthly package. Associated-company rules can change your rate — say if you control more than one company.

• Usually in: CT600, tax computation, accounts
• Often extra: R&D, personal SA100, enquiry defence, group work

How should I choose a corporation tax accountant?

Check ICAEW, ACCA, AAT or ICAS, then compare a package that includes accounts and the CT600. Ask who prepares the computation. Skip anyone who cannot name the two different corporation tax deadlines.

Online and local firms file the same return. Pick the cheaper quote on the same scope unless you need meetings. Authorise the firm as your HMRC agent after you have signed.

1. Write down your accounting reference date
2. Ask for quotes that include accounts and CT600
3. Flag R&D, other companies, or a director's loan up front
4. Diaries both the payment date and the filing date