Questions & Answers

Yes. You prepare your accounts once and Tax Optimiser uses the same figures to produce the iXBRL-tagged accounts, the tax computation and the CT600. The accounts are filed with Companies House, and the CT600, accounts and computation are submitted to HMRC, all directly from the app. Find out more about CT600 filing.

Micro-entity accounts under FRS 105, small company accounts under FRS 102 Section 1A, and dormant company accounts. Tax Optimiser guides you to the right standard when you set up the company.

Yes. You can connect Xero, QuickBooks or Sage to pull in your trial balance, or import a trial balance from a spreadsheet exported from any other bookkeeping software.

A Corporation Tax accounting period can never be longer than 12 months, so a longer period of accounts needs two CT600 returns: one for the first 12 months and one for the remainder. You prepare one set of accounts and Tax Optimiser splits the profits and produces both returns for you.

Yes. You can send the CT600, tax computation and iXBRL accounts to HMRC only, and mark the Companies House filing as not required. You still enter your accounts figures in Tax Optimiser so that it can produce the iXBRL accounts for HMRC, and they should match what you filed at Companies House. HMRC receives the full accounts including the profit and loss account, even if the version at Companies House shows only a balance sheet. The fee is the same. Read the step-by-step guide.

Yes. You can file for earlier accounting periods as well as the current one, and we do not charge more for a late return. Any late filing penalty is between the company and HMRC.

£10 + VAT (£12 including VAT) per company per accounting period, or £5 + VAT for a dormant company. One payment covers both the HMRC and Companies House filings for that period. A period longer than 12 months counts as one period, so the fee covers both CT600 returns. There is no extra charge for late periods, amendments or resubmissions. It is free to sign up and prepare your accounts and return, and you pay only when you are ready to submit. See our pricing.

The company's Unique Taxpayer Reference (UTR), its Companies House number, and the Government Gateway user ID and password for the company's Corporation Tax account. To file accounts at Companies House as well, you also need your Companies House presenter details and the company's authentication code.

If HMRC rejects a return, the reason HMRC gave is shown against the submission, so you can correct it and send it again at no extra charge. If you need to change a return after HMRC has accepted it, you can update the figures and submit it as an amended return from the same data, also at no extra charge. HMRC normally accepts amendments up to 12 months after the filing deadline.

Yes. Each submission is recorded in your account with its date, its status once HMRC has accepted it, and the IR Mark, which is HMRC's receipt reference for the return. You can also download the CT600, the computation and the accounts as PDFs for your records.

Sole traders and landlords must use Making Tax Digital for Income Tax from 6 April 2026 if their qualifying income from self-employment and property is over £50,000, from 6 April 2027 if it is over £30,000, and from 6 April 2028 if it is over £20,000. Qualifying income is based on the tax return for the tax year two years earlier.

No. The MTD for Self Assessment and VAT modules run independently of each other. You can use either module separately based on your needs.

Yes. You can carry on using your existing Excel spreadsheet as long as you calculate the 9-box VAT totals. Then you will need to specify in Tax Optimiser the sheet and cells to extract the data from. Finally, use our upload section to bridge the Excel file to send to HMRC.

Yes. We support Excel 97 onwards. We have also had clients successfully use our software with a range of other spreadsheet software. If you have any doubt, feel free to sign up and try it out.

Yes. As long as you are able to export an Excel/CSV file from your existing system or software, you can upload it to Tax Optimiser to extract the data and submit it to HMRC. All you need to do in the VAT settings is set what sheet and cells to extract the data from. We have had clients successfully use our software on a range of software including all versions of Sage Line 100, Sage Instant, Sage 50, Sage 200 and Access Dimensions.

No. As part of the new legislation, you cannot just manually add up the totals and key them into the spreadsheet. All the values need to be calculated either from software or formulas within the spreadsheet.

You will just need to output an Excel/CSV file with the 9-box totals calculated. You can then upload your Excel spreadsheet into our software to send it to HMRC.

Yes. There is the ability to add your own logos, brand colours and your own web address, e.g. https://mtd.acmeaccountants.com.

Yes. The Government Gateway user ID and password you enter for filing Corporation Tax returns are encrypted before they are saved, and our database is also encrypted at rest. Once saved, your password is never displayed again — not to you, your team, or our staff — and is only decrypted at the moment we send your return to HMRC. To change it, simply enter a new one.

For VAT and Making Tax Digital for Income Tax we connect using HMRC's own sign-in, so we never see your HMRC password for those at all.