Company tax return vs company accounts in 2026/27

For corporate practitioners operating in the 2026/27 financial year, distinguishing between the compliance pathways for statutory financial reporting and tax self-assessment remains a fundamental duty. While the preparation of these documents occurs simultaneously, the law treats them as two distinct statutory obligations, owed to two different government bodies, with misaligned deadlines.

When clarifying a company tax return vs company accounts for your clients, you must separate the requirements under the Companies Act 2006 from those under the Finance Act 1998, whilst ensuring compliance with strict new 2026 digital filing mandates.

Company Accounts (Statutory Financial Statements)

Company accounts provide a financial snapshot of the business’s performance over its accounting reference period. You prepare these documents primarily for the company’s shareholders and for public record at Companies House.

Legal Basis and Standard

Under section 394 of the Companies Act 2006 (CA 2006), the directors of every company bear a strict legal duty to prepare accounts for each financial year. Section 393 of the CA 2006 dictates the standard these accounts must meet: the directors must not approve the accounts unless they are satisfied that they give a “true and fair view of the assets, liabilities, financial position and profit or loss” of the company.

Filing Deadline and Recipient

You must file these statutory accounts with Companies House. Section 442 of the CA 2006 sets out the strict period allowed for filing. For a private company, the deadline is exactly nine months after the end of the relevant accounting reference period.

Example: If a private company’s accounting reference period ends on 31 December 2025, you must file the statutory accounts with Companies House by 30 September 2026.

Company Tax Return (CT600)

Unlike company accounts, the company tax return (form CT600) serves exclusively to quantify and declare the company’s Corporation Tax liability to HM Revenue & Customs (HMRC).

Legal Basis and Contents

Paragraph 3 of Schedule 18 to the Finance Act 1998 empowers an officer of Revenue and Customs to require a company to deliver a tax return detailing information “relevant to the tax liability of the company.

You must include the company’s self-assessment computation and attach a copy of the statutory accounts to this return to form a complete submission.

Deadlines: Filing vs. Payment

A critical distinction for the company tax return is the separation of the filing deadline from the payment deadline:

1. The Payment Deadline: Section 59D of the Taxes Management Act 1970 dictates that standard Corporation Tax is due and payable nine months and one day after the end of the accounting period.
2. The Filing Deadline: Under paragraph 14 of Schedule 18 to the Finance Act 1998, the statutory filing date for the CT600 return is generally twelve months from the end of the period for which the return is made.

Consequently, a company must pay its tax three months before it actually has to file the final return with HMRC.

The 2026/27 Context: CATO Closure and Software Mandates

If you are filing either document in the 2026/27 financial year, you must navigate a critical shift in HMRC’s digital infrastructure.

Previously, unrepresented companies could use HMRC’s free Corporation Tax online filing service (known as CATO – Company Accounts and Tax Online) to submit both their accounts to Companies House and their CT600 to HMRC.

HMRC officially closed this free service on 31 March 2026.  From 1 April 2026 onwards, you must use proprietary third-party commercial software to submit the CT600 and the accompanying iXBRL-tagged accounts.

Increased Penalties for Late Filing (FA 2026)

Failing to meet the distinct deadlines for these documents triggers severe financial penalties. For the 2026/27 tax year, the government aggressively increased the sanctions for late company tax returns.

Section 265 of the Finance Act 2026 amended Schedule 18 to FA 1998, doubling the flat-rate penalties for late tax returns due on or after 1 April 2026:

• The initial flat-rate penalty for missing the 12-month filing deadline increased from £100 to £200.
• A second consecutive failure to file on time attracts a £400 penalty.
• If the company fails to deliver a return for three consecutive accounting periods, the penalty jumps to £1,000, with further extended delays risking up to £2,000.

(Note: Companies House administers an entirely separate, escalating penalty regime for late-filed company accounts).

Summary Table: Company Accounts vs Company Tax Return

For completeness, practitioners should immediately audit their clients’ software subscriptions to ensure their existing accounting packages are fully compliant with the new third-party iXBRL filing mandates that came into force in April 2026, thereby preventing unnecessary exposure to the new £200 HMRC penalties.