Corporation Tax · CT600 + iXBRL

File your corporation tax and company accounts for £10

One price, both filings. Submit your CT600 and iXBRL accounts straight to HMRC and Companies House. Sync directly from Xero or QuickBooks, or upload your own spreadsheet. No subscription. No annual licence.

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No card required. Only pay £10 when you submit.

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Tax Optimiser CT600 computation screen showing the corporation tax payable and guided sections

A real CT600 computation in the app — no mock-ups.

HMRC recognised software for CT600 Companies House recognised software UK-built & supported No subscription — pay per submission

Built for directors and accountants alike

Whether you're filing for your own company or for clients, Tax Optimiser works the way you do.

Company directors

File your own corporation tax return and statutory accounts without needing an accountant. Our guided workflow handles the CT600 boxes, the iXBRL tagging, and the submission to HMRC and Companies House — £10 covers both filings for the year.

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Accountants and bookkeepers

Buy credits in bulk and bring per-filing cost down to £3. File CT600s for as many clients as you like, sync directly from each client's Xero or QuickBooks, and submit to HMRC and Companies House from one place.

See credit pack pricing →

From accounts to filed CT600 in three steps

1
Xero, QuickBooks and spreadsheet data syncing both ways with sales, expenses and assets in Tax Optimiser

Connect Xero or QuickBooks, or upload a spreadsheet

Link your accounting software in under two minutes using OAuth, or upload your own trial balance spreadsheet. We map the chart of accounts automatically — no manual re-keying.

2
Profit and loss review in Tax Optimiser with a disallowable column for add-backs such as depreciation

Review, map and adjust

Map your trial balance to the CT600 computation with our guided workflow. Post adjustment journals that sync back to your accounting system. Built-in validation flags issues before you submit.

3
Final step of the guided corporation tax submission wizard, ready to send the CT600 to HMRC

Submit CT600 + iXBRL and track deadlines

We generate iXBRL-tagged accounts and your CT600 and submit them directly to HMRC and Companies House from the app. Companies House deadline tracking is built in. You get confirmation receipts in minutes.

See exactly what you get

These are real screens from the app — the same ones our step-by-step user guide walks you through. No mock-ups, no surprises after you sign up.

Tax Optimiser dashboard showing the end of year wizard and setup progress for accounts and corporation tax

The End of Year wizard on the dashboard — real screen, no mock-ups.

Guided workflow

Start with a wizard, not a blank form

The End of Year wizard walks you through company details, trial balance, accounts review and submission in one guided flow — you can't get lost. Your numbers come in however you keep them: straight from Xero or QuickBooks, an uploaded spreadsheet, or keyed in by category.

Read the getting started guide →

Read the trial balance guide →

The computation

The tax maths is done for you

Add-backs, marginal relief, losses, the small profits rate — calculated automatically and shown in a computation you can actually read. Your corporation tax payable updates live at the top of the screen as you work, so there's never a surprise at the end.

Read the computation guide →
Generated corporation tax computation showing the 25 percent rate, marginal relief and tax payable

The generated computation, with marginal relief worked through.

Capital allowance pools in Tax Optimiser showing plant and machinery additions feeding the computation

Asset pools feeding the computation automatically.

Capital allowances

Capital allowances without the spreadsheet

Record asset additions once and let the app handle the pools — main pool, special rate, cars, structures and buildings. Annual Investment Allowance is allocated for you and everything flows straight into the computation and the CT600.

Read the capital allowances guide →
Filing

Guided submission to HMRC and Companies House

FRS 105 or FRS 102 1A accounts are built from the same trial balance and tagged as iXBRL automatically. Two short wizards validate, verify and review the documents, then send everything directly — your CT600 and computations to HMRC, your accounts to Companies House. Receipts arrive in minutes, and the deadline tracker updates itself.

Read the submission guide →

Read the documents guide →

Companies House submission wizard in Tax Optimiser showing the validation, verification, review and send steps

Validation, verification, review, send — the whole submission wizard.

Simple, honest pricing

One filing or a thousand — the more you buy, the less you pay. Working papers are included free with every filing.

Pay-as-you-go

£ 10 +VAT

per company, per year — covers both your statutory accounts and corporation tax submission

FRS 105 or FRS 102 1A accounts

Corporation tax (CT600) return

Direct Xero & QuickBooks sync

Automatic iXBRL tagging

Direct submission to Companies House and HMRC

Email support

Sign up free

For accountants and bookkeepers

One credit = one company, one year, both filings.

Pack Credits Price £ per credit
Pay-as-you-go1£10£10
Starter25£200£8
Practice100£600£6
Growth250£1,250£5
Scale500£2,000£4
EnterpriseBest value1,000£3,000£3

All prices exclude VAT. Credits do not expire.

Sign up to buy credits
The Tax Optimiser checkout showing a £10 submission fee plus VAT, £12 in total, paid securely through Stripe

This is the entire checkout. £10 + VAT when you submit — no subscription hiding behind it. Real screen, no mock-ups.

See every screen before you sign up

Our free user guide walks through the whole journey — from creating your first accounting period to the HMRC and Companies House receipts — using the same screenshots you've seen on this page. Read it online or download the PDF edition.

Frequently asked questions

One company's corporation tax return (CT600, filed to HMRC) and statutory accounts (filed to Companies House) for one financial year. Both filings, one fee.

Yes. We submit your CT600 and the iXBRL-tagged accounts and computations straight to HMRC, and your statutory accounts to Companies House, directly from the app. No third-party portals or filing tools.

Yes, fully automatic. We tag your accounts and computations to the current taxonomy without you needing to do anything. You don't need to know what iXBRL is to use Tax Optimiser.

Yes, with true two-way sync. We pull your trial balance from Xero or QuickBooks and push adjustment journals back, so what you file and what's in your books always match. You can also upload your own spreadsheet instead.

Yes. Companies House integration tracks your filing deadlines so you can stay compliant without watching the calendar.

Yes. You can prepare and submit amended corporation tax returns to HMRC from the app at no extra charge.

Yes. Accountants and bookkeepers can buy credits in bulk — one credit covers one company's CT600 and accounts for the year, with per-filing cost dropping to as low as £3. No per-seat fees or annual licence.

If you're filing for clients as an agent, you'll authorise submissions with your HMRC agent credentials. We'll walk you through connecting them during setup.

We're ICO-registered (ZA473706), and your data is encrypted in transit and at rest. We never sell or share your data. Read our Privacy Policy for full details.

File your CT600 for £10. No subscription. No surprises.

Sign up free. Connect your accounting software. Only pay when you submit.

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