A Corporation Tax
computation, shown working.
RepBud Revenue prepares a Corporation Tax computation from a real double-entry ledger — the two rates (19% and 25%) with marginal relief, and capital allowances (AIA and writing-down allowances) driven by your fixed-asset register. It produces the computation; your accountant files the CT600.
Two-rate CT · marginal relief · capital allowances · fixed-asset register
What the computation covers
Corporation Tax on a small company is not one flat rate any more. Revenue works from your taxable profit and applies the 19% small-profits rate and the 25% main rate, with marginal relief tapering in between — and it shows how it got there, so the figure is explainable rather than a number you have to take on trust.
Capital allowances come off your fixed-asset register: qualifying additions can take the Annual Investment Allowance, and the balance carries forward in a pool attracting writing-down allowances. Those allowances feed the taxable-profit figure the whole computation is built on, and because the register is part of the ledger, they tie back to the assets you actually bought.
It is honest about its edge: Revenue produces a computation and an estimate of the tax due, not a filed return. The CT600 and iXBRL accounts still go to HMRC through your accountant. RepBud is designed to assist, not replace, your professional judgement.
How Revenue helps
The parts of a CT computation, worked out
A CT computation, shown working
Taxable profit, adjustments, capital allowances and the tax due — laid out as a computation you can read and check, not a single figure with nothing behind it.
Two rates with marginal relief
The 19% small-profits rate and the 25% main rate, with marginal relief tapering between the profit limits — so the rate applied to your profit is explained, not assumed.
Capital allowances
Annual Investment Allowance on qualifying additions, with the balance carried in a pool attracting writing-down allowances, feeding straight into the taxable-profit figure.
Driven by the fixed-asset register
The register of what you bought, when and for how much is the source the allowances read from, so your capital allowances tie back to the assets actually on the books.
From a real ledger
The computation starts from your Profit & Loss on a genuine double-entry ledger, with every figure drilling down to the transactions behind it — traceable, not typed in.
Your accountant files it
Invite your accountant view-only to review the computation. Revenue produces the estimate and the working; the CT600 and iXBRL filing to HMRC stays with them.
Frequently Asked Questions
Corporation Tax questions
Does Revenue file my CT600 to HMRC?+
No. Revenue produces a Corporation Tax computation — an estimate of the tax due, with the working behind it — but it does not file the CT600 or the iXBRL accounts to HMRC. That filing is not built, so your accountant still makes it. We would rather be clear about that than imply a submission that is not there.
How does it handle the two Corporation Tax rates and marginal relief?+
The computation applies the small-profits rate of 19% and the main rate of 25%, with marginal relief tapering between the lower and upper profit limits. It shows how the rate was arrived at for your level of profit, so the figure is explainable rather than a single number with no working.
Does it calculate capital allowances?+
Yes. Capital allowances are driven by your fixed-asset register: qualifying additions can take the Annual Investment Allowance (AIA), and the balance carries forward in a pool attracting writing-down allowances. The allowances flow into the taxable-profit figure the computation is built on.
What is a fixed-asset register and where does it come from?+
It is the list of your capital assets — what you bought, when, for how much, and how it depreciates. Revenue keeps that register as part of the ledger, and it is the source the capital-allowances calculation reads from, so your allowances tie back to the assets actually on the books.
Is the computation based on real accounts?+
Yes. The taxable profit starts from your Profit & Loss on a genuine double-entry ledger, with the usual adjustments and capital allowances applied. Every figure drills down to the transactions behind it, so the computation is traceable rather than assembled by hand.
Can my accountant review the computation before filing?+
Yes. Invite your accountant as a view-only user and they can see the ledger, the fixed-asset register and the computation, then make any adjustments and file the CT600. RepBud is designed to assist, not replace, your professional judgement.
Can I bring my books across first?+
Yes. Revenue imports from Xero, QuickBooks and Sage — the guided importer in Settings moves your chart of accounts, contacts and opening balances, so a mid-year switch does not mean rebuilding the books from scratch.
Know the number early
See your Corporation Tax before year end
Start a 14-day free trial, bring your books across, and let Revenue prepare the computation — rates, marginal relief and capital allowances. No card required.
Start a free trial →