Do the CT600 and the company accounts have to match?

In short: Yes. The Company Tax Return (CT600) is worked out from the same statutory accounts the company files, so the figures must tie together. Taxable profit is usually different from the accounts profit, but it starts from it, and the computation must show "any adjustments made to the figures in the accounts" (GOV.UK: Company Tax Return guide). Taxley prepares the accounts and the CT600 from one set of figures for £39.95 with micro-entity accounts, and files the accounts at Companies House once the return is paid and the accounts are finished.

Take the 30-second check to see whether Taxley fits your company.

Key facts (checked on 11 October 2026)

Do the CT600 and the accounts have to show the same figures?

They must agree, but not every figure is the same. Turnover, profit before tax and the balance sheet in the return's attachments are the accounts themselves. The taxable profit on the CT600 is the accounts profit after tax adjustments, and the computation filed with the return must show how one becomes the other.

A company files its Company Tax Return with HMRC as three linked parts: the CT600 form, sent as XML data, plus the statutory accounts and the tax computation, normally attached in iXBRL (GOV.UK: Businesses XBRL guide). The accounts HMRC can require with the return are the accounts the Companies Act 2006 requires the company to prepare (FA 1998 Sch 18 para 11), so there is one set of accounts, not a separate "tax version". HMRC's return guide says the company must include computations that show how the figures in the return were calculated, with a separate calculation for each trade that shows any adjustments to the accounts figures (GOV.UK: Company Tax Return guide). In practice, that means a reader at HMRC can start from the profit in the accounts, follow each adjustment in the computation and land on the taxable profit in the CT600. If that trail breaks, the return is internally inconsistent, even if each document looks fine on its own.

Why is taxable profit different from the profit in the accounts?

Because the tax rules start from the accounts profit and then change it. Some costs in the accounts aren't deductible for tax, such as depreciation and client entertaining, and some tax reliefs never appear in the accounts, such as capital allowances. GOV.UK says the Corporation Tax profit "is different from the profit or loss shown in your annual accounts".

The starting point is the law: the profits of a trade are calculated in accordance with generally accepted accounting practice, subject to any adjustment the tax law requires or authorises (CTA 2009 s.46). The adjustments then pull the two figures apart. Depreciation is the accounts' way of spreading the cost of an asset, but the asset itself is capital spending, which isn't deductible from trading profits (CTA 2009 s.53); capital allowances give the tax relief instead (GOV.UK: Annual Investment Allowance). Business entertainment is generally not deductible at all (CTA 2009 s.1298). So a difference between the two profit figures is normal. What matters is that every pound of the difference is explained in the computation. Our guide to the bridge from accounting profit to taxable profit goes through the common adjustments line by line.

Which CT600 figures come straight from the accounts?

Turnover, the profit the computation starts from, and the Corporation Tax shown as owed in the accounts should all trace to the return. Turnover in box 145 is the accounts figure. Trading profits in box 155 are the accounts profit after adjustments. The tax charge in the accounts should normally equal the tax the computation works out.

Box numbers and wording were checked against HMRC's Company Tax Return guide on 11 October 2026. Turnover is a common slip: a company registered for VAT normally shows turnover without VAT in both places, which our guide to whether CT600 turnover includes VAT explains. Dates can differ legitimately: a first period of accounts longer than 12 months needs two CT600s, because an accounting period for Corporation Tax can't exceed 12 months (CTA 2009 s.10). First company accounts: why you may need two CT600s shows how one set of accounts covers both returns.

Must HMRC and Companies House get the same accounts?

Yes, the same accounts, though not always the same pages. HMRC gets the full statutory accounts with the return. A small company can deliver a shorter copy to Companies House, for example without the profit and loss account. The figures in both must come from the one set of accounts the directors approved.

The law lets a small company choose not to deliver its profit and loss account to Companies House, which is why "filleted" accounts exist (Companies Act 2006 s.444). That is a choice about what goes on the public register, not permission to prepare different figures. HMRC still receives the full accounts, including the profit and loss account, because the return needs the accounts the Companies Act requires (FA 1998 Sch 18 para 11). GOV.UK's guide to annual accounts says you can file with Companies House and HMRC together or separately, and that the accounts can be used to work out the Corporation Tax to pay (GOV.UK: Prepare and file annual accounts). If a company corrects its accounts after filing, the CT600 may need amending too, and the other way round. Our guide to filleted, abridged and full accounts explains what each version contains.

What happens if the CT600 and the accounts don't agree?

HMRC can ask why. It can open a compliance check into a return, normally within 12 months of the day it was filed, and an unexplained gap between the accounts and the return is the kind of question a check starts with. If the return understates the tax through carelessness, a penalty can follow.

The time limit for an HMRC enquiry is set by FA 1998 Sch 18 para 24: for a company that isn't in a large group, the window normally closes 12 months after the day the return was delivered. A careless inaccuracy that understates tax can bring a penalty of up to 30% of the extra tax, which an unprompted disclosure can reduce to nil (FA 2007 Sch 24 para 4 and para 10). The fix is usually an amendment: a company can normally amend its return within 12 months of the filing deadline (GOV.UK: Company Tax Returns: making changes). Our guide to a CT600 mistake found after filing covers what to check, and the compliance check guide covers what happens if HMRC writes first.

How does one set of figures flow through to the CT600?

Start with the accounts profit, add back what tax doesn't allow, deduct the tax-only reliefs, and the result is the taxable profit. The tax on that profit then goes back into the accounts as the tax charge and the amount owed. The example below, for a fictional company, shows every figure in both places.

Hollin Lane Design Ltd, a fictional company, has a 12-month year with turnover of £84,000 and costs of £52,000. The costs include £3,000 of depreciation and £600 of client entertaining. It bought a £4,000 computer during the year and claims the Annual Investment Allowance on it. It has no associated companies, so profits up to £50,000 are taxed at the small profits rate of 19% (GOV.UK: Corporation Tax rates).

The check runs both ways. £32,000 + £3,000 + £600 − £4,000 = £31,600, and £31,600 × 19% = £6,004. That same £6,004 is the tax charge in the profit and loss account and, until it is paid, the Corporation Tax owed in the balance sheet's creditors. If the accounts showed a tax charge of £6,500, either the computation or the accounts would be wrong, and the gap is worth finding before filing. The accounts profit and the taxable profit are different, yet the two documents agree, because the computation explains the £400 difference.

How does Taxley keep the CT600 and the accounts in step?

Taxley builds both from the figures you enter once. Your profit and loss account and balance sheet feed the accounts, the tax computation and the CT600, so turnover and profit can't drift apart between documents. When you change a figure, Taxley works out the tax again and rebuilds the documents before the return can be paid for.

Taxley (taxley.co.uk), UK online software that prepares and files the Company Tax Return (CT600) with HMRC and the annual accounts with Companies House, keeps one record of the company's figures for each return. You type them in or import a trial balance, and the iXBRL accounts, the computation and the CT600 are generated from that record. Taxley compares the Corporation Tax owed in your balance sheet with the tax it has worked out and, if they differ by more than rounding, lists likely causes and lets you use its figure. If you upload your own iXBRL accounts instead, Taxley checks that the company number, period, turnover, profit before tax and net assets agree with the return before it files. For the public register, Taxley files its own accounts at Companies House as a copy without the profit and loss account, built from the same figures, once the return is paid and the accounts are finished. If you upload your own accounts, you file them at Companies House yourself. It doesn't calculate deferred tax or give tax advice, so read the documents before you file. Take the 30-second check to see whether Taxley fits your company.

Frequently asked questions

Can the profit on the CT600 be different from the profit in the accounts?

Yes, and it usually is. The CT600's taxable profit is the accounts profit after tax adjustments, such as adding back depreciation and entertaining and deducting capital allowances. The computation filed with the return must show each adjustment, so HMRC can follow the difference.

Should turnover on the CT600 equal turnover in the accounts?

Yes. Box 145 is the turnover figure from the profit and loss account for the same period. If the company's period of account is longer than 12 months, the turnover is split between the two returns, but the two parts should add up to the accounts figure.

Can I file different accounts with HMRC and Companies House?

Not different figures. A small company may send Companies House a shorter copy without the profit and loss account, but HMRC receives the full statutory accounts. Both copies come from the one set of accounts the directors approved, so the balance sheet should be identical.

What if I find a difference after filing?

Work out which document is wrong. If the CT600 is wrong, amend it, normally within 12 months of the filing deadline. If the accounts are wrong, correct them at Companies House as well, then check whether the tax computation changes and amend the return if it does.

Does the Corporation Tax in the accounts have to match the return?

Normally, yes. The tax charge in the profit and loss account and the Corporation Tax owed in the balance sheet should equal the tax in the computation, unless there is a reason such as deferred tax or an earlier year's adjustment. Explain any difference before you file.

General information, not personalised tax or accounting advice.