Free CT600 filing software refers to HM Revenue and Customs (HMRC)-approved accounting and tax tools that allow limited company directors to prepare and submit Corporation Tax returns and statutory accounts without an upfront subscription.

Key Takeaways

• Free CT600 filing software options for UK limited companies have become extremely limited following the official retirement of HMRC’s legacy free online filing portal.
• Genuinely free Corporation Tax software is no longer available for standard company filings, as HMRC now requires businesses to use third-party software.
• Small business owners managing their own compliance must weigh the trade-offs between pay-per-filing utilities and traditional ongoing accounting software subscriptions.
• Micro-entities that qualify under FRS 105 can use low-cost digital tools for iXBRL tagging without paying high accountant fees.

What is a CT600?

A CT600 is the official tax return form issued by HM Revenue and Customs (HMRC) that UK limited companies, clubs, and other corporate entities must use to calculate and report their Corporation Tax liability.

The form records the company’s financial activity for the accounting period, including taxable profits, business expenses, capital allowances and any tax reliefs that apply.

Once completed, the CT600 must be submitted to HMRC digitally, along with the company’s statutory accounts in iXBRL format and its tax computation, within 12 months of the accounting period end.

Is there free CT600 Filing Software in the UK?

There is currently no genuinely free Corporation Tax software for UK limited companies that want to submit their statutory returns directly. While a few software packages offer free bookkeeping tiers or trial periods, completing and transmitting an official company tax return requires paid functionality.

• No Genuinely Free End-to-End Tools: Software providers that offer free plans restrict Corporation Tax modules and iXBRL generation to paid upgrades.
• Limits of Free Plans: Basic accounts preparation may be free, but submitting the return usually requires an annual subscription or a fee for each filing.
• Hidden Tagging Costs: Free spreadsheets and basic invoicing apps cannot create the structured format required by HMRC, so you may need a separate conversion tool.

In practice, small business directors looking to avoid costs have to choose between low-cost pay-per-filing tools and monthly accounting software.

What Happened to the HMRC Free CT600 Filing Software Tool?

HM Revenue and Customs (HMRC) retired its old online Corporation Tax filing service on 31 March 2026, ending direct digital submissions through the government service.

• The End of Direct Submissions: The closure ended the previous direct digital filing service. Small business owners and micro-entity directors can no longer log directly into a government web form to key in figures and submit their CT600 returns for free.
• Shift to Commercial Frameworks: The change means companies now have to rely on third-party commercial software. Companies must now submit through Government Gateway APIs provided by approved software developers.
• Outdated Technology Standards: HMRC decommissioned the portal because its underlying framework no longer met modern digital standards, nor did it accommodate updated requirements under the new tax year 2026 updates, company law, and the Economic Crime and Corporate Transparency Act.
• Integration of Advanced Calculations: Commercial software now fills the gap by providing features such as automatic tax calculations, marginal relief calculations and capital allowance schedules.
• Companies now have few alternatives beyond approved commercial software, professional agent accounts, accountants or pay-per-filing services.

Can I submit my Corporation Tax return myself?

Yes, you can submit your Corporation Tax return yourself without hiring an accountant, as long as you follow the required digital process. Since HMRC retired its direct online portal, managing the process independently requires navigating several structured steps:

1. Review the company accounting period end date and calculate the 12-month statutory filing deadline mandated by HM Revenue and Customs.
2. Gather all primary financial records, including bank statements, sales invoices, allowable business expenses, and director loan accounts.
3. Select an HMRC-approved software package or pay-per-filing digital utility matching the corporate structure.
4. Enter your financial figures into the software, which can then calculate trading profits, capital allowances and Corporation Tax due.
5. Generate the required Inline Extensible Business Reporting Language format for accounts and computations.
6. Use your Government Gateway login to authorise the submission and send the return electronically.
7. Download and save the electronic submission receipt and confirmation notification for corporate record-keeping compliance.

Can I file Form CT-600 without software?

No, most companies cannot submit Form CT600 without using third-party software. Manual or paper filing is only allowed in limited cases, such as for digitally excluded organisations or companies going through formal insolvency proceedings.

For other limited companies, filing without software is not available because of HMRC’s digital filing requirements.

• Mandatory Digital Links: Submitting a paper CT600 form is strictly restricted to specific exemption categories, such as digitally excluded organizations or companies under formal insolvency proceedings.
• iXBRL Tagging Requirement: HM Revenue and Customs mandates that company tax returns and statutory accounts must be submitted using Inline Extensible Business Reporting Language (iXBRL) formatting.
• Spreadsheet Incompatibility: Standard Excel spreadsheets or unformatted PDF documents cannot be read directly by government gateway intake systems without prior digital tagging.
• Risk of Rejection: Trying to file manually or bypass the approved digital channels can result in rejection and may lead to late-filing penalties.

What is the best CT600 software for small UK businesses?

The right third-party platform depends on how often you file, your budget and your bookkeeping needs. HMRC-approved options range from single-return pay-per-filing tools to comprehensive monthly accounting packages:

• Taxpipe: A pay-per-filing digital utility priced around £59 per filing, featuring included FRS 105 micro-entity iXBRL tagging. It suits small business owners who prefer avoiding ongoing monthly subscriptions.
• FreeAgent: A subscription service starting from £19 per month with iXBRL inclusion and high micro-entity suitability, frequently offered free of charge to business banking customers via providers like NatWest or RBS.
• Xero: A popular monthly bookkeeping suite starting from £15 per month, though its iXBRL generation typically requires an additional paid add-on module rather than being built natively into the base tier.
• TaxCalc: A robust desktop and cloud compliance suite starting from £199 per year, tailored primarily toward accountancy agents and businesses managing multiple complex portfolios.

CT600 Software Provider Comparison

Software Provider	Pricing Model	iXBRL Inclusion	Micro-Entity Suitability
Taxpipe	£59 per filing	Included (FRS 105)	High
TaxCalc	From £199 per year	Included	Medium (Agent focused)
FreeAgent	From £19 per month	Included	High
Xero	From £15 per month	Via add-on only	Medium

How can small business owners choose compliant HMRC-approved software?

When choosing third-party software, check that it meets the required standards and does not come with unexpected fees.

• Check HMRC Approval: Check the official government directory of commercial software suppliers to ensure the platform connects directly via Government Gateway APIs for both Corporation Tax and iXBRL accounts submission.
• Confirm FRS 105 or FRS 102 Compatibility: Match the software’s reporting standards to your company size. Micro-entities qualifying under FRS 105 need streamlined abridged accounts, whereas small companies require full FRS 102 compliance, often supported by specialized SME R&D tax credit claim modules.
• Check the Total Cost: Look past headline monthly subscription rates to identify hidden costs, such as separate fees for iXBRL tagging modules, multi-company licenses, or charges for submitting accounts to Companies House simultaneously.
• Check How It Works With Your Bookkeeping: Choose between standalone pay-per-filing utilities (if you maintain records via spreadsheets) or comprehensive accounting suites that automate data flow from bank feeds directly into your tax computations.

How can I file a company tax return without paying for monthly software?

You can avoid a monthly software subscription while still following HMRC’s digital filing rules by using these alternatives

• Use Pay-Per-Return Utilities: Instead of paying a monthly fee year-round, opt for transactional platforms like Taxpipe that charge a one-off fee per submission (around £59). This means you only pay when you need to file.
• Check Free Business Banking Perks: Many UK business bank accounts (such as NatWest, RBS, or Mettle) include free full access to invoicing and accounting software like FreeAgent as part of their banking package. Check your business banking package to see whether compliant software is already included.
• Use Free Bookkeeping with a Separate Tagging Tool: You can keep your daily records in a free spreadsheet or basic invoicing app, then move the data into a low-cost iXBRL tool when you are ready to file.
• Hire an Accountant for One-Off Submissions: If your business affairs are straightforward and software subscription costs outweigh your filing volume, hiring a licensed accountant to handle a single annual submission can sometimes match the cost of commercial software packages without the administrative hassle.

How do micro-entity accounts qualify for simplified filing?

Qualifying for simplified reporting under Financial Reporting Standard 105 (FRS 105) can reduce the amount of work involved, allowing micro-entity directors to prepare simpler accounts while keeping track of any Section 455 tax rate that applies to director loans.

To qualify, a UK limited company must satisfy at least two of the following three statutory thresholds for consecutive financial years:

• Turnover Threshold: The annual net turnover must not exceed £632,000.
• Balance Sheet Total: The aggregate balance sheet total (the total value of assets before deducting liabilities) must remain below £316,000.
• Staff Headcount: The average number of employees must not exceed 10 workers during the financial year.

If the company does not meet at least two of these criteria for two consecutive years, it will lose its micro-entity status and move to the standard small company reporting rules under FRS 102.

Conclusion

Managing Corporation Tax now requires more care when choosing software, following the retirement of the official government filing tool.

Limited company directors should consider how often they file, how complex their accounts are and their budget before choosing a monthly subscription or pay-per-filing service.

Keeping accurate digital records throughout the year makes it easier to stay compliant when the filing deadline arrives.

Disclaimer: This information is for educational purposes and does not constitute formal legal or financial advice; consult a qualified accountant or HMRC guidelines for your specific corporate situation.

FAQs

Can I file my company tax return CT600 online without third-party software?

No, direct manual filing through government portals is unavailable because HMRC retired its free online tool, requiring all limited companies to use commercial software or an accountant.

What is the cheapest corporation tax software in the UK?

Pay-per-filing digital utilities like Taxpipe offer single-submission pricing around £59 per return, avoiding ongoing monthly software subscription overheads.

What is the best free software to file accounts with HMRC?

There is currently no genuinely free software in the UK that handles the full Corporation Tax filing process and iXBRL generation.

Do free CT600 software packages include iXBRL tagging?

No. Free accounting plans typically do not include iXBRL tools, so users may need to buy a separate tagging tool or upgrade to a paid plan.

Are there penalties for late Corporation Tax submissions?

Yes, filing a company tax return after the statutory 12-month deadline triggers automatic fines starting at £100, which escalate significantly with prolonged delays.

Can I file Companies House accounts and HMRC tax returns together?

Yes, some comprehensive accounting suites allow joint submission sessions, whereas specialist tax utilities handle the HMRC return separately from Companies House statutory filings.

What happens if I make an error on my CT600 submission?

To amend a submitted return, log back into your approved software, correct the relevant figures and submit the amended return to HMRC.