CT600 Corporation Tax Software

File UK Corporation Tax CT600 Returns in minutes.

Prepare your CT600, generate iXBRL accounts and tax computations, and submit to HMRC.

Start Your CT600 Return

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Main CT600 Profit, adjustments, reliefs and Corporation Tax calculation.
Directors’ loans Support for loans to participators.
iXBRL included Accounts and computations generated for online filing.

HMRC’s old Company Tax Return service has closed

From April 2026, companies need commercial software to file a CT600, Corporation Tax computation and company accounts online. #GoFile gives you a guided way to prepare and submit the return without heavyweight accountancy software.

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File your CT600 in minutes.

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  • Set up your company in seconds

    Add company details and start your Corporation Tax filing path.

  • Prepare CT600 and computations

    Keep your return, accounts and tax computation together.

  • Attach iXBRL accounts

    Include the company documents HMRC expects.

  • Submit directly to HMRC

    File your CT600 online when you are ready.

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Built for HMRC online CT600 filing

CT600, iXBRL accounts and tax computations in one guided workflow.

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What is a CT600?

A CT600 is the UK Company Tax Return used to tell HMRC about a company’s income, profits, reliefs, tax calculation, payments and Corporation Tax due for an accounting period. A CT600 normally needs supporting company accounts and a tax computation, both filed digitally in iXBRL format.

Who files it? UK limited companies and other organisations within Corporation Tax.
When is it due? Usually 12 months after the end of the accounting period.
What is attached? Statutory accounts and a Corporation Tax computation in iXBRL.
Can you file yourself? Yes. You can file yourself with software, or your accountant can file for you.

What #GoFile handles

CT600 software built for real small-company filing work.

Not a generic form filler. #GoFile follows the Corporation Tax workflow accountants and owner-managed companies actually need at year end.

Main CT600 return

Capture company details, accounting period, turnover, taxable profits, deductions, payments and the final Corporation Tax position.

Tax computation generated

Turn accounts profit into taxable profit with add-backs, deductions, capital allowances, losses and current Corporation Tax rates.

iXBRL accounts

Generate digital accounts and computation attachments for HMRC filing, with FRS 105 and FRS 102 small-company workflows.

Directors’ and shareholder loans

Report close company loans to participators, repayments, write-offs and s455 tax alongside the main Corporation Tax return.

Marginal relief and rates

Calculate small profits rate, main rate, marginal relief, associated company threshold adjustments and split accounting periods.

File Corporation Tax to HMRC

Send the CT600 to HMRC, monitor filing status, download confirmations and keep a clear filing history for each company.

Guided workflow

From year-end figures to HMRC submission.

#GoFile is designed to make Corporation Tax filing feel ordered: the company, the period, the accounts, the tax calculation, the review, then the submission.

Find the company and set the period

Enter the company number, UTR and accounting period so the return is built around the right legal entity and deadline.

Add or import year-end figures

Use the guided financial sections, or import account figures to quick-fill the return and supporting accounts data.

Review the calculation

Check taxable profit, marginal relief, payments already made, balance due and any directors’ loan schedule before filing.

Submit to HMRC

Generate the iXBRL attachments, sign the declaration and submit the CT600 through the secure filing workflow.

CT600 filing checklist Ready
Company details and UTRChecked
Accounting period12 months
Accounts standardFRS 105 / FRS 102
Tax computationGenerated
Directors’ loan scheduleOptional
iXBRL attachmentsIncluded
HMRC submissionFinal review

Accountants and SMEs

One Corporation Tax product, two very different filing pressures.

Practices need repeatable workflow and client pricing. Company owners need a clean way to file one return without buying a heavy practice suite.

For accountants

Add Corporation Tax to the same #GoFile environment you already use for client filing. Keep pricing flexible, add CT only where needed, and give the team a guided CT600 workflow.

  • Manage multiple companies and clients from one login.
  • Add Corporation Tax as an active service for discounted agent pricing.
  • Prepare CT600 returns without moving clients into a heavyweight tax suite.
  • Use filing history and confirmations to keep the practice trail clean.
Start as an accountant

For SMEs without an accountant

File one company return when your books are ready. #GoFile keeps the CT600 process in plain English while still handling the digital filing requirements behind the scenes.

  • Start from £49.99/year for Corporation Tax as one active service.
  • Use the guided flow for simple small-company Corporation Tax returns.
  • See what is due, when it is due, and what HMRC will receive.
  • Download accounts, computation and confirmation records.
File one company

Deadlines and digital filing

Built around the Corporation Tax dates that catch people out.

The CT600 deadline and the Corporation Tax payment deadline are not the same date. #GoFile surfaces the period, return due date, payment position and filing status in the workflow so a company can avoid last-minute uncertainty.

CT600 filing deadline The Company Tax Return is normally due 12 months after the end of the accounting period.
Payment deadline Corporation Tax is usually payable 9 months and 1 day after the accounting period ends.
Loss-making companies A company may still need to file a CT600 even if it made a loss or has no Corporation Tax to pay.
iXBRL requirement Accounts and computations are normally filed digitally in iXBRL with the Company Tax Return.

Research the rules

Corporation Tax guides that support this page.

CT600 Company Tax Return What the return covers and what gets submitted. iXBRL Digital Filing Why accounts and computations need machine-readable tags. Directors’ Loans How overdrawn loan accounts are reported and taxed. Corporation Tax Calculator Estimate CT with current UK rates and marginal relief.

Ready to File CT600?

Start with one company, or add Corporation Tax to an existing #GoFile plan for a practice workflow that covers VAT, Income Tax and Corporation Tax in one place.

Get started with Corporation Tax

Corporation Tax CT600 FAQs

Straight answers for the searches people actually make before choosing CT600 software.

What is a CT600 Company Tax Return?

A CT600 is the Company Tax Return sent to HMRC for a company’s Corporation Tax accounting period. It reports the company’s income, profits, reliefs, payments and tax due.

How do I file a CT600 online in the UK?

You file electronically using Corporation Tax software, HMRC’s online service for eligible simple returns, or an accountant. For most filings, the CT600 goes with company accounts and a tax computation in iXBRL format.

Does #GoFile support directors’ loans on a CT600?

Yes. #GoFile supports directors’ and shareholder loan details for close company loans to participators, including repayments, write-offs and the s455 tax summary. HMRC labels this supplementary page CT600A.

If you searched for CT600L for directors’ loans, the official HMRC loan schedule is CT600A. CT600L is used for R&D and creative industry tax credits.

Do I need iXBRL accounts and computations?

Usually, yes. Corporation Tax returns are filed online and the supporting accounts and tax computation are normally submitted in iXBRL, so HMRC can process the data digitally. #GoFile can generate these attachments for supported small-company returns.

How much does Corporation Tax software cost?

For SMEs filing one company, Corporation Tax filing starts at £49.99/year for one active service. Accountants can add Corporation Tax to an agent plan with discounted client pricing.

Can a small company file a CT600 without an accountant?

Yes, if your company return is straightforward and you have the correct company details, accounts figures, Corporation Tax information and HMRC credentials. More complex companies may still need specialist advice.

When is a CT600 due?

The CT600 is normally due 12 months after the end of the accounting period. The Corporation Tax payment deadline is usually earlier: 9 months and 1 day after the accounting period ends.

Does a company need to file if it made a loss?

A company may still need to send a Company Tax Return even if it made a loss or has no Corporation Tax to pay, especially where HMRC has issued a notice to deliver a return.

Current filing facts checked against GOV.UK guidance on Company Tax Returns, Corporation Tax rates, directors’ loans, CT600A and CT600L.