Is cheap CT600 software safe? What to check before you pay

In short: Cheap CT600 software can be safe, but the price won't tell you. Directors stay legally responsible for the company's accounts and Company Tax Return (CT600) whatever the software cost (GOV.UK: Directors' responsibilities running a limited company). So check what it produces, which companies it covers, whether Companies House filing and VAT are included, and how it uses your Government Gateway login. Taxley charges £44.50 (promotion price until 31 Dec 2026; £89.00 from 1 Jan 2027) for a return with micro-entity accounts, including filing the accounts at Companies House.

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

Is cheap CT600 software safe to use in 2026?

Yes, cheap CT600 software can be safe in 2026 if it produces everything your company's return needs and files it correctly. A low price isn't a risk in itself. The risk is paying for software that covers less than your company needs, such as micro-entity accounts only, HMRC filing without Companies House, or no supplementary pages.

HMRC's free filing service closed on 31 March 2026, so companies now file through commercial software. HMRC's guidance tells you to consider which elements you need and make sure the software lets 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). In our check of 15 products' own pricing pages on 27 September 2026, published prices ran from £5 to £96 for a dormant company's return, £15 to £166.80 for a micro-entity trading company, and £25 to £258 for a small company with FRS 102 accounts, with VAT added where a product said its price excluded it. Price and completeness didn't line up: some £20 products included Companies House filing, while one at £59 didn't. A low price therefore tells you little about safety either way; our guide to the best CT600 filing software compares product types side by side.

Who is responsible if cheap software gets your company tax return wrong?

The company and its directors are responsible, not the software supplier. GOV.UK says directors can hire others for day-to-day tasks but stay legally responsible for the company's records and accounts (GOV.UK: Directors' responsibilities running a limited company). Every return also carries a declaration that it is correct and complete to the best of the signer's knowledge (FA 1998 Sch 18 para 3).

A careless error in the return can cost the company a penalty of up to 30% of the extra tax due. Under Schedule 24 to the Finance Act 2007, a penalty applies when a return contains an inaccuracy that understates tax, overstates a loss or inflates a repayment claim, and the inaccuracy was careless or deliberate (FA 2007 Sch 24 para 1). "Careless" means a failure to take reasonable care. For an error on a UK matter the maximum is 30% for careless, 70% for deliberate and 100% for deliberate and concealed (para 4). Telling HMRC about a careless error before you have reason to believe HMRC has found it, or is about to, can cut the penalty to 0%; a prompted disclosure can cut it to 15% (para 10). Nothing in those rules depends on what the software cost, and blaming a £5 product won't turn a careless figure into a careful one.

HMRC judges reasonable care by what the person did, measured against a prudent and reasonable person in the same position (CH81140). HMRC's manual expects someone who meets an unfamiliar transaction to find out the correct treatment or take advice, and, if still unsure, to point out the entry when sending the return (CH81120). No penalty is due for an inaccuracy made despite reasonable care. In practice, reasonable care with any software means reading the accounts and computation it produces before you file, checking the figures against your records, and paying for advice on anything you don't understand. Our guide to common CT600 mistakes when filing yourself lists the errors worth checking for first.

What does HMRC's list of Corporation Tax software actually mean?

HMRC's list shows suppliers who have given evidence that their software can produce one or more parts of a Company Tax Return. It is not a recommendation. HMRC says it can't recommend or endorse any product over another, doesn't support the products, and doesn't carry out any security testing of them (GOV.UK: List of commercial software suppliers for Corporation Tax).

HMRC's list, last updated on 29 September 2026, had 49 suppliers in its "Produce and submit CT600" table, 37 of them marked "Suitable for self-filers" (GOV.UK: List of commercial software suppliers for Corporation Tax). The table's columns show only whether a product can produce and submit a CT600, submit iXBRL documents, and suits self-filers. The columns say nothing about price, accounts types, Companies House filing, supplementary pages or support. A "Yes" in every column therefore doesn't prove a product fits your company, and HMRC also says it won't be responsible for any loss arising from using the software. Treat HMRC's list as a starting point, not a verdict. Our guide to choosing software now HMRC's filing service has closed has questions to send each supplier. Wording on any supplier's website isn't a substitute for the list itself, so check the current version on GOV.UK if a listing matters to you (GOV.UK: List of commercial software suppliers for Corporation Tax). HMRC changes the list as suppliers join and leave.

What should you check before buying CT600 software?

Check eleven things before you pay: the files it produces, the pages and accounts it covers, whether Companies House filing and VAT are included, what happens after a rejection, how you pay, and how it protects your data and Gateway login. HMRC says companies should make sure their software is adequate for their reports (GOV.UK: Businesses XBRL guide).

The first three rows decide whether the software can produce your return at all. HMRC says it is compulsory for companies to send accounts and computations in iXBRL, and unacceptable for most to attach them as PDFs (GOV.UK: Businesses XBRL guide). Supplementary pages, such as the CT600A for a loan to a director, form part of the return and are covered by its declaration (GOV.UK: Completing your Company Tax Return). Accounts scope matters as much: a company is a micro-entity only if it meets 2 of 3 tests, which are turnover of £1 million or less, a balance sheet of £500,000 or less, and 10 or fewer employees (GOV.UK: Micro-entity, small and dormant company accounts). A company outside those limits can't file micro-entity accounts, so a micro-only product can't prepare its return, however low its price. Our guide to iXBRL accounts and why a PDF won't do explains what to look for in the files.

The middle rows decide what the filing really costs. HMRC's closure guidance says companies still need to file annual accounts with Companies House (GOV.UK: Closure of HMRC's file-your-accounts-and-tax-return service), so a price that covers only HMRC leaves a second job, and a private company that files its accounts up to a month late pays a £150 penalty (GOV.UK: Penalties for late filing of annual accounts). VAT matters because a company can reclaim VAT on business purchases only if it is VAT-registered (GOV.UK: Charge, reclaim and record VAT: Charging VAT). At the standard rate of 20%, a "£100 plus VAT" price costs an unregistered company £120. A yearly subscription can be good value if you use the product every year, but a company that stops trading or closes should know how to cancel before the renewal date. The rejection row matters because an accepted return by the deadline is what counts, not the first attempt.

The last three rows protect your data and your login. A company that processes personal data must pay the Information Commissioner a data protection charge unless all its processing is exempt (Data Protection (Charges and Information) Regulations 2018, reg 2), and the ICO publishes a searchable register of fee payers (ICO register). HMRC says you must not share your HMRC sign-in details with anyone, including a tax agent (GOV.UK: Keeping your HMRC sign in details safe). Software that files in the company's own name asks for the company's Government Gateway user ID and password when you submit, so ask where you type them and whether the password is stored afterwards.

What are the warning signs of risky CT600 software?

Four warning signs stand out: a price with no clear VAT statement, a price that covers HMRC but not Companies House, a request for your Government Gateway password by email, and no way to preview the accounts before paying. None proves a product is unsafe, but each is a reason to ask more questions first.

• No clear VAT statement. In our check of 14 products' published prices on 27 September 2026, 8 didn't say whether VAT was included, and the other 6 quoted prices before VAT. For a company that isn't VAT-registered and can't reclaim it (GOV.UK: Charge, reclaim and record VAT: Charging VAT), an unclear price can turn out 20% higher.
• An HMRC-only price. In the same check, at least 3 of the 14 priced products didn't include Companies House filing, and another charged extra for it. The company still has to file its accounts with Companies House (GOV.UK: Closure of HMRC's file-your-accounts-and-tax-return service).
• A request for your password by email. GOV.UK tells you not to give out private information such as passwords if you're not sure a message is genuine (GOV.UK: Report internet scams and phishing). Type the company's Government Gateway login only into the filing software's own submission screen, never into an email, a phone call or a chat.
• No accounts preview before paying. Without a preview you can't check the accounts and computation against your records, which is the reasonable-care step HMRC looks for (CH81120).

Narrow scope isn't a warning sign on its own, but it has to match your company. In our 27 September 2026 check, at least 7 of the 14 priced products covered only micro-entity or dormant companies, one capped profit at £50,000, and another limited property companies to £5,200 of turnover. Those limits are fine if your company fits inside them, so check the micro-entity tests on GOV.UK before choosing a micro-only product (GOV.UK: Micro-entity, small and dormant company accounts).

Is cheap software worse than expensive corporation tax software?

Not necessarily: price and completeness didn't line up in our 27 September 2026 check. Some £20 products included Companies House filing, while one at £59 didn't. Only 5 products, Taxley included, published a confirmed price for small-company FRS 102 accounts, from £25 to £258. So compare what each price includes before comparing the numbers.

Higher-priced options often bundle something other than a safer filing. In our check, one bookkeeping subscription with a CT600 module cost £198 including VAT in its first year and £396 a year after that; it can be good value if you keep your books in it all year, but its own help pages said it handles most micro-entities rather than every company. One desktop tax product cost £170.40 including VAT for a year's licence, yet it needed separate accounts-production software to make the iXBRL accounts and didn't file with Companies House. A per-filing web service charging under £100 can therefore do more of the job than a product costing nearly twice as much. Our guide to how much it costs to file a CT600 sets the price ranges out by company type.

Cheap software is usually enough for a dormant company or a simple trading company with ordinary sales and costs. An accountant is worth paying for when the return involves R&D relief, a loss carry-back, a group, an overseas activity or an accounts treatment you aren't sure about, because reasonable care may mean taking advice (CH81120). The deadline is the same either way: 12 months after the end of the accounting period, with a penalty for filing late (GOV.UK: Company Tax Returns: Overview). Our page on whether you need an accountant lists the cases where paying for advice makes sense, and the Corporation Tax deadline calculator works out your dates.

How does Taxley measure up against the checklist?

Taxley, which publishes this guide, is one worked example of the checklist, with limits as well as answers. It prepares iXBRL accounts and a computation, and files the CT600 with HMRC and the accounts with Companies House in one fee.

Taxley charges one fee per return, and you pay only when you choose to file: £9.50 (promotion price until 31 Dec 2026; £19.00 from 1 Jan 2027) for a dormant company, £44.50 (promotion price until 31 Dec 2026; £89.00 from 1 Jan 2027) with micro-entity accounts and £84.50 (promotion price until 31 Dec 2026; £169.00 from 1 Jan 2027) with small-company FRS 102 accounts (pricing). You can prepare the return and preview the CT600, computation and iXBRL accounts before paying anything. Against the dormant prices that 12 other products published on 27 September 2026, Taxley's current dormant price is the 3rd-lowest of the 13 that publish a price for that case, among the lowest-priced for a dormant company, and its small-company FRS 102 price was the 2nd-lowest of 5 products that publish a price for that case. The fee also covers filing the accounts at Companies House, which uses the company's authentication code, which Companies House says you need to file using commercial software (GOV.UK: Company authentication codes for online filing).

Before Taxley takes payment, its readiness checks must be clear: it won't charge while a required item is missing, such as an unbalanced balance sheet or a blank declaration. Some entries that HMRC's business rules would reject, such as capital allowance boxes that are out of use for the period, are blocked before payment too, and no fee is taken for documents that fail HMRC's format check. Those checks don't catch every possible rejection. If HMRC rejects a return, you can correct it and resubmit the same filing at no extra charge, a route HMRC's guidance allows (GOV.UK: Closure of HMRC's file-your-accounts-and-tax-return service); the fee isn't refundable once a return has been sent, unless the failure was caused by Taxley.

Taxley files with the company's own Government Gateway user ID and password, typed into its submission screen when you file. Taxley uses them only to send that return and never keeps the password; the user ID is kept, encrypted, with the submission record. Support is by email, Monday to Friday, 9am to 5pm UK time. Taxley doesn't suit every company: it doesn't handle R&D relief, terminal loss claims or medium-sized and audited companies, and it doesn't file confirmation statements, which Companies House requires separately (GOV.UK: Directors' responsibilities running a limited company). Take the 30-second check to see whether Taxley fits your company.

Frequently asked questions

Is it safe to file a company tax return with cheap software?

Yes, if the software produces everything your return needs and you check its output before filing. Safety comes from scope and your own review, not the price. The company stays responsible for the return, and a careless error can cost a penalty of up to 30% of the extra tax.

Does HMRC test CT600 software for security?

No. HMRC's software list says it doesn't carry out any security testing of developer products or services, and it encourages users to ask suppliers about security. Check the supplier's ICO registration and ask how it stores your data and Government Gateway login.

Should you choose CT600 software on price alone?

No. Compare what each price includes first: iXBRL accounts and computation, your accounts type, supplementary pages, Companies House filing and VAT. In our 27 September 2026 check, some £20 products included Companies House filing while one at £59 didn't.

Can you switch software if a cheap product can't file your return?

Yes. HMRC says a rejected return can be re-filed using commercial software, on paper to the Corporation Tax office or through an agent. File within 12 months of the end of the accounting period to avoid a late-filing penalty, whichever product you use.

General information, not personalised tax or accounting advice.