Tax Optimiser

Tax Optimiser: cloud filing for CT600s, statutory accounts and Making Tax Digital

Tax Optimiser is a British cloud-based tax filing platform aimed at small companies, their directors, accountants and bookkeepers, as well as sole traders, landlords and VAT-registered businesses. Its core proposition is joint filing: preparing statutory accounts and the CT600 corporation tax return from the same figures and submitting the accounts to Companies House and the return to HMRC in a single step. The company presents this as a replacement for HMRC's free Company Accounts and Tax Online service, which it states closed on 31 March 2026.

Accounts and corporation tax in one workflow

The software prepares statutory accounts under FRS 105 (micro-entity) or FRS 102 Section 1A alongside the CT600. According to the company, it builds the tax computation, capital allowances and supplementary pages, tags everything in iXBRL, and files both outputs. A guided workflow with built-in HMRC and Companies House validation is intended to catch errors before submission, and the site points directors to a corporation tax calculator for estimating the bill beforehand.

Integrations and data entry

Xero and QuickBooks connections pull in the trial balance, which the platform maps to the corporation tax computation and statutory accounts using AI; year-end adjustment journals are pushed back into the books so the filed figures match the ledger. Accountants on Sodium can sync their clients as well. Users without accounting software can import a trial balance from a spreadsheet. Entering a company number populates the registered office, directors, accounting periods and filing deadlines from Companies House.

Making Tax Digital: VAT and Income Tax

For MTD VAT, the company describes HMRC-recognised software that submits returns directly from an Excel spreadsheet or from Excel or CSV exports produced by Sage, Access Dimensions or other packages, and that lets users view VAT liabilities and payments. Because it is cloud based, no plugins or desktop installation are required: users identify once which sheet and cells hold their figures and then upload the same spreadsheet each period. For MTD for Income Tax, the software handles quarterly updates and the final declaration for self-employment and UK property income. The site notes that since April 2026 sole traders and landlords with qualifying income over £50,000 must keep digital records and send quarterly updates, with the threshold falling to £30,000 in April 2027 and £20,000 in April 2028; qualifying income is defined as combined self-employment and property income before expenses.

Dormant companies and other returns

Dormant company accounts are filled in from Companies House data and filed for £5 + VAT; where HMRC has issued a notice to deliver a Company Tax Return, a nil CT600 is included. The product list also covers working papers, SA100 Self Assessment (beta) and SA800 Partnerships (beta).

Pricing structure

The headline price is £10 + VAT (£12) per company per year for the CT600 and statutory accounts filed together. Accountants and bookkeepers work from credit packs starting at £3 per company filing. MTD VAT and MTD for Income Tax cost £30 + VAT a year, free for the first year for individual organisations. The company frames its pricing as a deliberate contrast with older tax software built for accounting firms with large IT budgets.

Background and recognition

Tax Optimiser Ltd was founded in Britain in 2018 by Mark O'Grady, who still leads the product and is described as having more than 20 years' experience building accounting software, including work with Sony and Tata. The company traces its origins to Intuit's SmallBizHack in 2017, where it won Best Integration with QuickBooks, and later won Xero's XDHAX developer challenge for innovative use of its API. O'Grady is also the founder of Mighty, an accounting solution for one-person limited companies. The site states that the platform is HMRC recognised for MTD VAT and Companies House recognised software, and that it has been used by 15,000 organisations and 700 accountants, with £4.6 billion in VAT submitted. It also reports a Google rating of 5.0/5 from 33 reviews.