Best CT600 filing software in the UK (2026): how to choose

In short: No CT600 product is best for every company: the right one prepares what you can't produce yourself, at the lowest total price including VAT. In September 2026 we found published prices from £5 to £195 plus VAT a return for software that files a dormant, micro or small company's CT600. HMRC's free filing service closed on 31 March 2026 (GOV.UK: Closure of HMRC's file-your-accounts-and-tax-return service). Taxley charges one fee per return, £44.50 (promotion price until 31 Dec 2026; £89.00 from 1 Jan 2027) with micro-entity accounts or £84.50 (promotion price until 31 Dec 2026; £169.00 from 1 Jan 2027) with small-company accounts, including filing the accounts at Companies House.

Taxley publishes this guide and sells CT600 software. We've described Taxley using the same checks as every other type of product, including its limits, such as the reliefs and company sizes it doesn't support. For the full cost of filing, including penalties and the accountant route, see how much it costs to file a CT600.

What is the best CT600 filing software in the UK in 2026?

The best CT600 filing software for a small UK company in 2026 is the lowest-priced product that covers every part of the return you can't produce yourself. HMRC says the software you choose should let you file a CT600, a Corporation Tax computation and your company accounts (GOV.UK: Closure of HMRC's file-your-accounts-and-tax-return service).

If an accountant already supplies accounts and a computation, CT600-only software is enough. If you're starting from your bookkeeping figures, you need a product that prepares all three. Companies House is a separate filing with its own deadline, so check whether the product files your accounts there too. The table sets out the main types of product on those points; the order isn't a ranking.

Based on the pricing and scope pages of 14 CT600 products, checked on 24 September 2026 on each supplier's own website.

How did we research CT600 software for this guide?

We are Taxley, a CT600 software vendor, so this guide has a conflict of interest. To limit it, we describe products by type rather than by name, we used only facts suppliers publish about their own products, and we describe Taxley's gaps as plainly as any other product's.

On 24 September 2026 we checked the pricing and scope pages of 14 CT600 products on their own websites: those named most often in search results and comparison pages for "best CT600 software" that month, plus several low-cost options we found while looking for cheaper routes. We looked at three things: scope (whether the product prepares the CT600, the tax computation and iXBRL accounts, and whether it files accounts to Companies House), price transparency (whether the full price and VAT treatment are published), and who the product is built for (dormant, micro-entity or small companies, or accountants). We didn't test any product's calculations, and we haven't used ratings or reviews.

Companies House filing is part of the scope check because it's a separate legal obligation. Private companies must deliver accounts to Companies House within 9 months of the end of the accounting reference period (GOV.UK: Preparing and filing Companies House accounts), while the CT600 is due within 12 months of the end of the accounting period (GOV.UK: Company Tax Returns: Overview). From 1 April 2028, accounts can only be filed with Companies House using commercial software (GOV.UK: Preparing and filing Companies House accounts); our guide to software-only accounts filing from 2028 explains what changes.

Which type of CT600 software suits which company?

The deciding question for most small companies is who prepares the accounts, because that fixes which type of product you need. A dormant company needs only a nil CT600 and dormant accounts, and half of the 14 products we checked publish a separate, lower price for dormant companies.

A micro-entity trading company needs FRS 105 accounts, a computation and the CT600, which pay-per-return and subscription products generally cover. A company that has outgrown the micro-entity limits needs FRS 102 Section 1A small-company accounts, which rules out micro-entity-only products: several low-cost pay-per-return products, the subscription products we checked and some bookkeeping software list micro-entity accounts only. If your accountant already produces iXBRL accounts and a computation, you only need software that submits the CT600. Our guide to micro-entity versus small-company accounts explains which applies to you.

What does each type of CT600 software offer?

CT600 products fall into five main types, plus the option of an accountant. Pay-per-return and subscription web services prepare accounts, computation and CT600 from your figures; bookkeeping software produces them from your records; CT600-only software needs accounts prepared elsewhere; and professional tax software is sold to accountancy practices.

Within each type, the price depends on the accounts size supported (micro-entity only, or small companies too), whether Companies House filing is included and whether VAT is added. Each profile below uses what suppliers of that type published on their own websites on 24 September 2026: what the type does, who it suits, its usual strengths and its limitations.

Pay-per-return filing software

Pay-per-return filing software is a web service that prepares the CT600, the Corporation Tax computation and iXBRL accounts from figures you enter, and charges once for each return you file. Most let you prepare and preview a return free and pay when you submit. More than half of the pay-per-return products we checked include Companies House accounts filing in the price; one charges extra for it, and some don't offer it. Taxley includes it in the price. Some support only micro-entity (FRS 105) accounts, while others also prepare FRS 102 Section 1A small-company accounts. Some prices include VAT, some add it at checkout and some pricing pages don't say. Some include amendments, re-filings or fixing a rejected return in the price, and one also sells a managed service where its team files for you.

Best for: dormant, micro-entity and small companies that file once a year and want to pay only when they file.

• Pro: you pay only when you file, with nothing to renew.
• Pro: accounts, computation and CT600 are prepared together from one set of figures.
• Pro: preparing and previewing is usually free, so you can check the scope before paying.
• Con: Companies House filing isn't always included: some products charge extra and some don't offer it yet.
• Con: supplementary pages vary; at least one product we checked doesn't support group relief (CT600C) or R&D relief (CT600L).

Annual-subscription filing software

Annual-subscription filing software covers the same ground as pay-per-return software, the CT600, computation and iXBRL accounts, but charges a yearly fee instead of a fee per return. The subscription products we checked include Companies House accounts filing in every plan, publish a lower dormant-company plan, and in one case let a single plan cover two or three companies. Both state that they support micro-entity companies only. You can usually prepare a return and preview the accounts free, but filing needs a subscription, and where the VAT treatment was stated, VAT was added on top.

Best for: micro-entity directors who file every year and want HMRC and Companies House filings under one yearly fee.

• Pro: Companies House accounts filing was included in every subscription plan we checked.
• Pro: lower yearly plans for dormant companies.
• Pro: some plans cover more than one company.
• Con: charged every year, whether or not you file.
• Con: the ones we checked support micro-entity accounts only, so no FRS 102 Section 1A small-company accounts.

Bookkeeping software with a CT600 module

Bookkeeping software with a CT600 module produces a limited company's accounts and CT600 from the records you already keep in it, so figures aren't entered twice. The bookkeeping product we checked pre-fills most CT600 boxes from your records, includes a tax calculation and a CT600A for an overdrawn director's loan, and files FRS 105 micro-entity accounts to Companies House as well as the CT600 to HMRC. It's a monthly or yearly bookkeeping subscription rather than a fee per return, although it was free for customers of certain business bank accounts.

Best for: micro-entities that already keep their books in software that includes a CT600 module.

• Pro: accounts and CT600 come from your bookkeeping, so figures aren't entered twice.
• Pro: can file accounts to Companies House as well as the CT600 to HMRC.
• Pro: free for customers of some business bank accounts.
• Con: otherwise it's a bookkeeping subscription, not a fee per return.
• Con: FRS 102 Section 1A small-company accounts may not be supported, so check before you rely on it.

CT600-only and desktop tax software

CT600-only software submits the return but expects your accounts, and sometimes the computation, to be prepared elsewhere and attached in iXBRL. It comes either as a web service's CT600-only tier, charged per return, or as downloadable desktop tax software bought as a yearly licence, which in some editions also covers the directors' personal Self Assessment returns. Companies House accounts filing usually isn't part of this type, because the accounts come from another package or from your accountant.

Best for: directors whose accountant supplies finished iXBRL accounts and a computation, and who want to submit the CT600 themselves.

• Pro: you don't pay for accounts preparation you already have.
• Pro: some desktop editions also cover the directors' Self Assessment returns.
• Con: accounts must come from another package or an accountant.
• Con: Companies House accounts filing usually isn't included.

Professional tax software for accountancy practices

Professional tax software is sold to accountancy practices that prepare and file CT600s for many clients. The practice product we checked was priced as a monthly subscription plus a per-user fee, with contract terms that vary, and it isn't designed for a director filing one company's return. We didn't assess its Companies House filing, so ask the supplier if that matters to you. Taxley's own practice workspace is described on CT600 software for accountants and practices.

Best for: accountancy practices filing many clients' returns, not single companies.

• Pro: built for volume, with many clients in one system.
• Con: priced and contracted for practices, not for one company's yearly return.

Using an accountant instead

An accountant prepares the accounts, computation and CT600 and files them for you, and can advise on the judgements behind the figures. Fees depend on the work your company needs, and we haven't found a credible published survey of what UK accountants charge, so this guide doesn't quote a range. An accountant matters most for R&D relief claims, loss carry-back or an uncertain accounts treatment; our do I need an accountant? page sets out which returns still need one.

Should you choose online or desktop CT600 software?

Online (cloud-based) CT600 software runs in your browser, so you can work from any computer while the supplier handles updates and storage; desktop software is installed on one computer, and you keep the files and backups. HMRC's software list doesn't say which is which, so check what each product prepares, not just where it runs.

The difference is where the software runs and where your figures sit. Online software runs in a web browser: the supplier hosts it, updates it and stores your data, so check where the data is held, whether it is encrypted and whether two-factor sign-in is offered. Desktop software is installed on your own computer: you keep the files, take the backups and install updates, and it is often sold as a yearly licence. Either way the return goes to HMRC online, because HMRC says sending accounts or computations on paper or as a PDF is unacceptable for most companies (GOV.UK: XBRL guide for UK businesses).

Taxley is online software. Its data is held on a server in London, and identifiers such as the UTR, and the documents it generates, are encrypted at rest; the security page sets out the details, including optional two-factor sign-in.

Is pay-per-return or subscription CT600 software better value?

Neither type of CT600 software is cheaper by design: pay-per-return software charges only when you file a return, while a subscription charges monthly or yearly whether or not you file. Pay-per-return tends to suit one company filing once a year; a subscription can suit several companies, or bookkeeping you'd pay for anyway. Compare the full year's cost.

For pay-per-return Corporation Tax software, the year's cost is the fee for each return you file, plus any extra for Companies House filing, larger accounts or supplementary pages such as the CT600A. For a subscription, it is the monthly payments or the yearly fee plus any add-ons, and the plans we checked covered micro-entity accounts only. First accounts covering more than 12 months are usually split into two Corporation Tax accounting periods, each with its own return (GOV.UK: Accounting periods for Corporation Tax), so check whether a per-return price counts that as one return or two. Ask whether VAT is added, because it raises a price quoted before VAT by 20%. Companies House lists no fee for filing annual accounts, so any charge for it is the software's (GOV.UK: Companies House fees).

Taxley is pay-per-return and charges one fee when a long first period is split into two returns; its fees are on the pricing page.

Where does Taxley fit among these types?

Taxley, the publisher of this guide, is pay-per-return filing software: it prepares a company's CT600, Corporation Tax computation and iXBRL accounts together, and files the return to HMRC using the company's own Government Gateway login. It charges once per return, with no subscription, from £9.50 for a dormant company to £84.50 with small-company accounts (pricing), including the accounts filed with Companies House. These are promotion prices.

Taxley prepares FRS 105 micro-entity or FRS 102 Section 1A small-company accounts. It covers director's loans (CT600A and section 455 tax), group relief, capital allowances, and chargeable gains on most sales of UK property and shares bought in one go, and it splits a first period longer than 12 months into two returns. It carries a trading loss back 12 months, files older years back to accounting periods that started on 1 April 2020, and amends a return it filed once HMRC has accepted it. Preparing and previewing is free; you pay only when you file. What you can file with Taxley lists each company type and filing job.

Best for: directors of small trading, property or dormant companies who want accounts, computation and CT600 prepared together at one price per return.

• Pro: no VAT is charged, and there is no subscription.
• Pro: small-company (FRS 102 Section 1A) accounts as well as micro-entity accounts.
• Pro: handles CT600A, group relief, the full CT600E for charities, loss carry-back and a long first period split into two returns.
• Pro: files the accounts at Companies House at no extra cost (it doesn't file the confirmation statement).
• Con: not for R&D relief claims, terminal loss claims, medium-sized or audited companies, or accounting periods that started before 1 April 2020.
• Con: accounts you uploaded yourself, and revised accounts for a period Companies House already has, aren't filed there by Taxley; you file those yourself.

What should you check before you pay for CT600 software?

Check nine things before you pay for CT600 software: whether it files to HMRC itself, whether it files your accounts at Companies House, which accounts it prepares, whether it produces iXBRL, how and when you pay, whether you can preview first, which periods it can file now, what it doesn't support and how support works.

The answer to each should be on the supplier's own pricing, scope or help pages. If one isn't published, ask the supplier before you pay.

1. Does it file to HMRC itself, or only prepare the return? Some products produce a return that you submit elsewhere. Ask whether it submits the CT600 to HMRC and whose Government Gateway login it uses.
2. Does it file your accounts at Companies House too? That is a separate filing with its own deadline. Ask whether it is included in the price and what you must supply, such as the company's authentication code. Companies House currently charges no fee for annual accounts (Companies House: Companies House WebFiling Help and Support), so a product without Companies House filing leaves you a separate, free filing to make yourself.
3. Which accounts does it prepare? Dormant, micro-entity (FRS 105) and small-company (FRS 102 Section 1A) accounts need different support, and some products cover only some of them. Micro-entity-only products can't produce FRS 102 Section 1A small-company accounts.
4. Does it produce iXBRL accounts and an iXBRL computation? Ask whether it prepares both with the CT600, or expects you to supply them from somewhere else.
5. How is it priced, and when do you pay? Per return, by subscription or inside a bookkeeping subscription. A subscription recurs monthly or yearly, while a per-return fee is charged for each return you file. Ask whether VAT is added (it adds 20% to a price quoted before VAT) and whether payment is taken before or after you have seen the finished return.
6. Can you preview the finished return before paying? Ask what you can see and save for free.
7. Which accounting periods can it file now? Products differ in the periods they can file today. Ask which accounting periods it can file and what happens to a later one.
8. What doesn't it support? Ask for the list, for example R&D relief, loss claims, group relief, charities, long first periods, amendments and confirmation statements, and which supplementary pages it handles. A company with a director's loan outstanding at the end of its accounting period may need a CT600A, covered in our guide to the CT600A and section 455 tax.
9. How does support work? Ask where to send a question, who answers it and whether the supplier gives tax advice or supports only the software.

How Taxley answers these questions

• Files to HMRC: yes, using the company's own Government Gateway login.
• Companies House: yes, at no extra cost. Taxley files the accounts it prepared, live since 28 September 2026, once the return is paid and finished, using the company's 6-character authentication code. It doesn't file uploaded accounts, accounts Companies House already has, first accounts for a period that doesn't start on the date of incorporation, or confirmation statements.
• Accounts and iXBRL: dormant, micro-entity (FRS 105) and small-company (FRS 102 Section 1A) accounts, prepared in iXBRL together with the CT600 and the tax computation.
• Pricing: one fee per return, with no subscription and no VAT, charged only when you file. The current fees are on the pricing page.
• Preview: preparing and previewing the CT600, the computation and the accounts is free.
• Periods: it splits a first period longer than 12 months into two returns.
• Not supported: R&D relief and medium-sized or audited companies. Which loss claims, older periods and amendments Taxley handles today is listed in the FAQ.
• Support: by email and through the contact page. Taxley is software, not an accountant or tax agent, and doesn't give tax advice.

Our guide to choosing CT600 software now HMRC's service has closed has a shorter checklist, and how to file a CT600 yourself walks through the filing itself. If a return involves R&D relief, loss carry-back or an uncertain accounts treatment, see do I need an accountant? before choosing software. If you're weighing Taxley, take the 30-second check to see whether Taxley fits your company.

Frequently asked questions

What is the cheapest CT600 software in 2026?

In September 2026 the lowest published prices we found were £5 for a dormant nil return and £20 for a micro-entity trading company with Companies House filing, both from low-cost pay-per-return products. A low headline price can still cost more overall, so check VAT, Companies House filing and accounts size. Taxley's small-company price was the 2nd-lowest of 5 products that publish one (checked 27 September 2026).

Is there free CT600 filing software?

HMRC's free online service closed on 31 March 2026. In September 2026 the only £0 route we found for a trading company was bookkeeping software that was free for customers of certain business bank accounts. Most other products let you prepare and preview a return free but charge when you file.

Which CT600 software also files accounts to Companies House?

Most pay-per-return products and the subscription products we checked include Companies House accounts filing; some charge extra for it, and some don't offer it. Taxley includes it in the fee per return. CT600-only and desktop tax software usually doesn't. Companies House charges no fee for annual accounts, so filing them yourself costs only time.

Do I need CT600 software if my accountant prepares my accounts?

Only if you file the CT600 yourself. If your accountant supplies finished iXBRL accounts and a computation, CT600-only software, either a web service's CT600-only tier or desktop tax software, can submit the return. Otherwise, ask your accountant to file it as part of their work.

Is Taxley the best CT600 software?

Not for every company. Taxley suits small companies that want accounts, computation and CT600 prepared together at one price per return. It files the accounts at Companies House too, though some low-cost products publish lower prices. The 30-second check shows whether Taxley fits your company.

General information, not personalised tax or accounting advice. Suppliers change their prices and features: check each supplier's own pricing page before you buy.