Making Tax Awesome
File your CT600 and company accounts together for £10
HMRC and Companies House recognised software for company directors and accountants, plus MTD for Income Tax and MTD VAT for sole traders, landlords and VAT-registered businesses
Start filing with HMRC & Companies HouseMTD VAT and ITSA free for individual organisations for the first year
Officially recognised & integrated
Recognised
Recognised
Xero connected
QuickBooks connected
UK tax software for CT600s, company accounts and Making Tax Digital
Everything a small company, sole trader or accountant needs to file online with HMRC and Companies House
CT600 corporation tax returns and statutory accounts in one
Prepare your statutory accounts (FRS 105 micro-entity or FRS 102 Section 1A) and your CT600 corporation tax return from the same figures. We build the tax computation, capital allowances and supplementary pages, tag everything in iXBRL, and file the accounts to Companies House and the CT600 to HMRC in one go.
Fully integrated with Xero and QuickBooks
Connect Xero or QuickBooks and we pull in your trial balance and use AI to map it to your corporation tax computation and statutory accounts. Year-end adjustment journals go back into your books, so what you file matches your ledger. No accounting software? Import a trial balance from a spreadsheet instead.
Companies House data filled in for you
Enter your company number and we fill in your registered office, directors, accounting periods and filing deadlines from Companies House. Dormant company accounts take a few minutes and cost £5 + VAT.
MTD for Income Tax for sole traders and landlords
Since April 2026, sole traders and landlords with qualifying income over £50,000 must keep digital records and send quarterly updates to HMRC. The threshold falls to £30,000 in April 2027. Our MTD for Income Tax software handles quarterly updates and the final declaration for self-employment and UK property income.
MTD VAT returns and Excel bridging
Our HMRC recognised (opens in a new tab) MTD VAT software submits your VAT return straight from your Excel spreadsheet, or from an Excel or CSV export from Sage, Access Dimensions or any other package. You can also view your VAT liabilities and payments.
Keep your spreadsheet, with nothing to install
Tax Optimiser is cloud based, so there are no plugins or desktop software to install. Tell us which sheet and cells hold your figures once, and each quarter or VAT period you upload the same spreadsheet you already use. Most of our users never change how they keep their records.
Who Tax Optimiser is for
HMRC closed its free Company Accounts and Tax Online service on 31 March 2026, so small companies can no longer file their accounts and CT600 together through HMRC. Tax Optimiser files both, together, for £10 + VAT.
Company directors
File your own year-end accounts and corporation tax return without an accountant. A guided workflow and built-in HMRC and Companies House validation catch mistakes before you submit. Use the corporation tax calculator to estimate your bill first.
Accountants and bookkeepers
Produce accounts, CT600s, working papers and VAT returns for your whole client list from one dashboard, with Xero and QuickBooks sync. Credit packs start at £3 per company filing.
Sole traders, landlords and VAT-registered businesses
Send MTD for Income Tax quarterly updates and MTD VAT returns to HMRC from the spreadsheet or bookkeeping software you already use. Free for the first year for individual organisations, then £30 + VAT a year.
Honest pricing for the businesses doing the actual filing
Most UK tax software was built decades ago for accounting firms with enterprise IT budgets. The prices reflect that — and the legacy.
We started Tax Optimiser at Intuit’s SmallBizHack in 2017, winning Best Integration with QuickBooks, and went on to win Xero’s XDHAX developer challenge for the most innovative use of its API. From day one we asked one question: why does software that submits a single form to HMRC need to cost hundreds of pounds a year?
The answer turned out to be “it doesn’t.” A modern cloud stack, no salespeople and customers who happily tell their accountant about us — that’s how we keep filing your CT600 at £10 instead of £100. See how our CT600 and accounts pricing compares, or view all prices.
Tax Optimiser Ltd was founded in London in 2018 by Mark O’Grady, who still leads the product today.
What you get for the price
HMRC recognition
Companies House recognition
AI-categorised trial balance from Xero and QuickBooks
I recently used Tax Optimiser for the first time to submit my accounts to Companies House and HMRC, and I’m thoroughly impressed. The platform is remarkably easy to manage, walking you through the entire process without any complex jargon. On top of that, their prices are extremely competitive. It saved me a ton of time and stress—I will definitely be using them again next year.
I had next to no confidence that Tax Optimiser could handle accounts submission and Corporation Tax. But I gave it a whirl… Both Companies House and HMRC have initially accepted the submissions… I previously filed on professional software and I paid about £1500. This is dirt cheap.
Excellent software. Very affordable if you're doing your own small company accounts. Links with Xero… Tax Optimiser has been a complete life saver for me.
20 years building accounting software
Mark O’Grady has been building accounting software for more than 20 years and has worked on every part of it, from bookkeeping and bank feeds to year-end accounts, corporation tax and VAT. Along the way he has worked with blue-chip companies including Sony and Tata.
Part of the team that won Sage Developer of the Year
Winner at Xero XDHAX and Intuit QuickBooks SmallBizHack
Winner at the HMCTS Online Courts Hackathon, where he met the Lord Chief Justice
Mark is also the founder of Mighty (opens in a new tab), a complete accounting solution for one-person limited companies.
“I really enjoy building software in the accounting space.”
15 thousand
Happy Organisations
700 accountants
Accountants
4.1 billion pounds
VAT Submitted
Frequently asked questions
Popular guides: filing your first CT600 · dormant company accounts · full vs filleted accounts · getting started with MTD VAT