If you're searching for free CT600 filing software, here is the truth nobody selling software will lead with: there isn't any.The free route was HMRC's own service, and it closed on 31 March 2026. Everything now on offer is a paid product — some merely dressed as free. Here's what actually changed, what filing yourself now costs, and how to decide whether it's still worth doing.
Since 2011, the joint HMRC / Companies House online service let a small company file its statutory accounts and its Company Tax Return in one sitting, for nothing. That is the thing that closed on 31 March 2026. From 1 April 2026, HMRC's guidance is one line long: use commercial software.
The only exceptions are paper filing with a reasonable excuse HMRC agrees to, or filing in Welsh. Neither is a strategy.
So every search result promising free CT600 filing in 2026 resolves to one of three things: a free trial, a free tierwhere the actual submission is paywalled, or a lead magnet for an accountancy service. That's not a scandal — software costs money to build — but you should know the menu before you order.
If a genuinely free CT600 filing route ever appears — from HMRC, a vendor, or anyone else — we'll email you once to say so. That's the whole deal.
Three parts, and the software subscription is the smallest of them:
Anywhere from around £20–£60 a year for a bare single-company filing to £200–£300+ for a fuller package. HMRC publishes a list of recognised suppliers — but it carries no prices and no recommendations, by design. You're comparison-shopping unaided.
Your accounts and computations must be tagged in iXBRL — every figure labelled so HMRC's systems can read it. The software assists; the judgement about which tag fits which line is yours, and it's where DIY filings go quietly wrong.
The old service filed to Companies House in the same sitting. Now that's a separate job — though accounts can still go to Companies House free via its own WebFiling service (until that too becomes software-only in April 2028); only some CT600 products bundle it in. Miss the separation and you're on one of two penalty ladders.
The stakes rose too: the late-filing penalty now starts at £200the day the CT600 is late (gov.uk has updated the figure — most articles still say £100), and the deadlines run on their own clock whether or not you've picked a product. All three deadlines are untangled in our CT600 deadlines guide.
If you filed happily through the old service, understand your own accounts, and your company is simple — one trade, no unusual items — buying software and carrying on is a perfectly reasonable choice. Budget the subscription, a weekend of setup, and real care over the tagging.
The honest arithmetic changes when your time has a price. The subscription plus the hours plus the risk of a mis-tagged filing often costs more than having it done — which is why the closure quietly turned many self-filers into clients of someone. The trick is noticing that before a deadline does it for you.
And if your company is dormant, stop before buying anything: you can tell HMRC it's dormant for Corporation Tax, and once they confirm, no return is needed unless HMRC issues a fresh notice to deliver one (typically when it trades again). Companies House still gets dormant accounts and a confirmation statement — a much smaller job.
We built a short checker for exactly this decision: it asks how your company filed before, whether it's trading or dormant, and how you feel about doing the tagging yourself — and gives you a straight answer about your options, with your real deadlines pulled live from Companies House.
No. HMRC's free online filing service closed on 31 March 2026, and since 1 April 2026 Company Tax Returns must be filed through commercial software. Paper filing is only accepted if you have a reasonable excuse that HMRC agrees to, or if you're filing in Welsh. Products advertising themselves as free are typically free trials, free tiers with the actual filing paywalled, or lead magnets.
It ranges widely — from around £20–£60 a year for a bare single-company filing, to roughly £120–£200 for a product that does the CT600 and tags your accounts in iXBRL, up to £200–£300+ for fuller practice-grade suites. That's a market observation, not an official figure — HMRC's own list of recognised suppliers deliberately carries no prices and, in its own words, is not able to recommend or endorse any one product over another.
iXBRL is a machine-readable format: every figure in your accounts gets an invisible label saying what it is, so HMRC's systems can read them. Your accounts and computations must be tagged in iXBRL to file the CT600. The software helps, but choosing the right tag for each line is judgement work — and it's where DIY filings most often go quietly wrong.
Sometimes. HMRC's supplier list notes that some of the listed products let you file your return and annual accounts together — but many are HMRC-only, leaving Companies House as a separate job. Check before you buy, because from 1 April 2028 Companies House accounts must also be filed through software, so an HMRC-only product buys you a second shopping trip in 2028.
Maybe not. If the company is dormant for Corporation Tax you can tell HMRC, and once they confirm, you don't need to file another Company Tax Return unless HMRC later issues a fresh notice to deliver one (for example when you start trading again). You must still file annual accounts and a confirmation statement with Companies House. Sorting the dormant status properly is usually a much better move than buying software to file nil returns.
The penalty is £200 the day the return is late — a figure gov.uk updated, though much of the internet still says £100 — and another £200 at 3 months. At 6 months HMRC estimates your bill and adds 10% of the unpaid tax, and another 10% at 12 months. Late three times in a row, and the £200s become £1,000 each. Deciding slowly is the most expensive option on this page.
We file accounts and CT600s through our own professional software — you never buy a licence, learn iXBRL, or watch a deadline. Book a free call and we'll tell you honestly whether you even need us.
Book a free call →General guidance, not advice for your specific situation. Software prices are market observations, not quotes. Last reviewed 14-07-2026.
We checked these rather than relying on memory. Every figure and deadline above comes from HMRC directly — go and read them yourself if you'd like to.
Last reviewed 14-07-2026. Tax rules change — if you're reading this long after that date, check the source.
