Tax prep support
Corporation tax return preparation support
Finbryn prepares the Corporation Tax computation and CT600 return for UK limited companies from your closed statutory accounts, including capital allowances and group relief, then hands the draft to a registered agent to review and lodge with HMRC before the filing deadline, 12 months after your accounting period ends.
Tax working papers
Illustrative client · August 2026
GBP
- Year-end books closed and reconciledDone
- Fixed asset and depreciation scheduleDone
- Book-to-tax adjustments listedDone
- Supporting schedules for the preparerIn progress
- Handed to the signer for review and filingNext
Illustrative. An example of the document, not a client's figures.
Built from statutory accounts, not a blank return
A Corporation Tax computation starts with your statutory accounts, prepared to FRS 102 or FRS 105 depending on your company's size. We build the tax computation directly from those accounts, adjusting for items treated differently for tax than for accounting purposes, such as depreciation and certain provisions, so the return reconciles cleanly back to the numbers your directors have already seen.
Two deadlines, not one
Corporation Tax is due for payment 9 months and 1 day after your accounting period ends, while the CT600 return itself is due 12 months after that same period end. Most companies that miss a date miss the payment one, because it lands three months before the filing one, and we track both separately rather than treating them as a single event.
Capital allowances and group relief
We build a capital allowances schedule covering plant, machinery and any qualifying structures, and where your company sits inside a group, we prepare the workpapers for group relief and loss surrender between companies before the return is drafted.
Who lodges the return
We prepare the computation and draft return. A registered agent holding an HMRC Agent Services Account, operating under money laundering supervision, reviews and lodges the return itself; we do not file it directly. HMRC's mandatory adviser registration scheme, which opened its first phase in May 2026, means that agent's own registration is checked before every filing season.
Micro-entity thresholds
If your company qualifies as a micro-entity, with turnover up to £1,000,000 and a balance sheet total up to £500,000, FRS 105 applies and the computation is generally simpler. We confirm which regime applies to your accounts each year rather than assuming last year's answer still holds.
Where this fits
This follows on from monthly bookkeeping and pairs with VAT return preparation if your company is also VAT registered. See pricing for Corporation Tax preparation rates.
Questions
Frequently asked questions: Corporation tax return preparation support
Who actually lodges our CT600 with HMRC?
A registered agent holding an Agent Services Account and money laundering supervision reviews and lodges the return we prepare.
When is Corporation Tax due?
Payment is due 9 months and 1 day after your accounting period ends, while the CT600 return itself is due 12 months after that same date.
Do you prepare the statutory accounts as well?
Yes, as part of your monthly close, and the tax computation is built directly from those same accounts.
What if our company qualifies as a micro-entity?
Companies with turnover up to £1,000,000 and a balance sheet total up to £500,000 report under FRS 105, which we confirm applies before starting the computation.
What happens if our accounting period is not exactly twelve months?
A shortened or extended first accounting period changes both the payment and filing deadlines, since both are calculated from the period end date rather than a calendar year. We flag the correct dates for your specific period rather than assuming a standard twelve-month cycle.
Do you also prepare the statutory accounts?
We prepare the underlying accounts as part of bookkeeping and close, then build the tax computation from them.
Who files the return?
A credentialed signer with the required agent authorisation files the return we prepare.
What software works with corporation tax return preparation support?
Corporation tax return preparation support runs inside Xero or QuickBooks Online, whichever you already use. If you are not yet set up in either, we can configure a file in your name so you keep ownership of it once the engagement is under way.
How do we get started with corporation tax return preparation support?
Getting started with corporation tax return preparation support begins with a short review of your current records and software access. Once that is done we confirm scope and timing in writing, and ongoing work begins on the schedule agreed with you.
Related services
- Tax prep supportVAT return preparation support (Making Tax Digital)Preparation support for quarterly VAT returns filed through Making Tax Digital, built from digitally linked records in your accounting software.
- BookkeepingMonthly bookkeepingOngoing monthly bookkeeping: transactions sorted into categories, accounts reconciled and month-end reports delivered in the software you already use.
Industries
- Professional servicesBookkeeping for professional service firms such as engineering, architecture and IT consulting billing clients by project or retainer.
- Real estate and property managementBookkeeping for property owners and managers tracking income, expenses and reserves at the level of each individual property.
Next step
Talk to the team that would run your books
A short call covers your setup, your software and what a first month would look like. You get a written scope and price after it.