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Checklist · Internal
CT600 Preparation Checklist for Accountants
Everything to collect, check and review before a corporation tax return leaves your desk.
Built by a practising Chartered Accountant · Unlimited users · 60-day free trial · Last updated 27 September 2026
Quick answer
A CT600 preparation checklist covers the records you need from the client, the accounts adjustments to review, the claims and reliefs to consider, and the sign-off steps before filing. In Remindoo each stage becomes a sub-task on a recurring corporation tax job, so every company follows the same route.
What records do you need before starting a CT600?
Finalised statutory accounts, the trial balance, bank statements, loan and director account detail, fixed asset additions and disposals, and any correspondence with HMRC.
Most delays are caused by missing detail rather than missing accounts: unexplained director account movements, no invoices for capital additions, and no answer on whether a cost was business or personal. Ask for those specifics in the original records request rather than discovering them at review.
Which adjustments and claims should be reviewed every time?
Disallowable expenditure, capital allowances including full expensing where relevant, losses, R&D where applicable, loans to participators and any associated company considerations.
Build the review as a fixed list rather than professional memory. Each item gets a yes, no or not applicable, recorded on the job. That way the reviewer can see what was considered, not only what was claimed.
What should happen before filing?
A second-person review, client approval of the accounts and computation, confirmation of the tax payable and payment date, and a record of the approval.
Keep the approval evidence on the client record, alongside the filing confirmation. When a query arrives two years later, the trail matters more than anyone's recollection.
Checklist preview
0/8 done · showing 8 of 24 itemsThe full 24-item checklist is in the download below. Enter your name and email to get it as a Word or PDF file.
This is a standard checklist. Each firm's requirements may vary, so please cross-check everything against current GOV.UK, Companies House and professional body guidance before relying on it.
See it working with your own clients
A 30-minute walkthrough using your services, deadlines and templates.
Turn this into a task and subtask template in Remindoo
Save each group as a task with subtasks, attach it to the right service and let recurring tasks create it for every client, every period. Each item gets an owner and a deadline, and nothing depends on someone remembering to print the list. See task and subtask templates.
Task and subtask templates
Checklists that make every job consistent.
See featureService templates
Repeatable structures for every service.
See featureRecurring tasks
Repeat work is created automatically on schedule.
See featureInternal vs external deadlines
Build a buffer before every statutory date.
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See featureWhat are the common mistakes?
- Starting the CT600 before the accounts are final
- No fixed list for reliefs and claims
- Missing director loan account explanations
- Client approval taken verbally
- Not diarising the payment date separately from the filing date
“Managing deadlines and tasks is much easier.”
Frequently asked questions
When is a CT600 due?
Generally twelve months after the end of the accounting period, with corporation tax payable earlier. Check GOV.UK for the dates that apply to your client.
Does Remindoo file the CT600?
No. Remindoo manages the workflow, deadlines and approvals; filing happens in your tax filing software.
Should the filing and payment dates be separate tasks?
Yes. They fall on different dates and often need different chasing, so keep them as separate tracked deadlines.
How do I make sure reliefs are always considered?
Use a fixed sub-task list on every corporation tax job so each relief is explicitly marked considered or not applicable.
Can the checklist be used for a first-year company?
Yes, with extra attention to the accounting period dates and any long or short first period.
Who should review the return?
Someone other than the preparer. Even in a small firm, a structured second look catches the most costly errors.
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Sources
Last updated 27 September 2026. General guidance, not regulatory advice.
Why recording every task matters in an accountancy practice
Accounting firms run on deadlines: VAT returns, payroll, confirmation statements, accounts and Self Assessment. Recording every job as a task, with an owner and a date, is the simplest way to make sure nothing is missed.
Avoid penalties
HMRC and Companies House charge penalties for late filing. A task for every deadline, with an internal date before it, gives the team a buffer.
Nothing depends on memory
Recorded tasks mean work continues when someone is off sick, on leave or has left the firm.
Consistent quality
Subtask checklists make every job follow the same steps and reviews, whoever does the work.
Visibility for managers
Filters by owner, status and deadline show at a glance what is late, what is due and who needs help.
Practical tips from UK practice
- Set an internal deadline two to four weeks before every statutory deadline.
- Use recurring tasks for repeat work such as VAT, payroll and bookkeeping.
- Break larger jobs into subtasks, including a review step.
- Comment on the task instead of by email, so the history stays with the work.
Related Remindoo features
Written and reviewed by Waqas Sagar ACA FCCA FMAAT, Chartered Accountant with 18+ years in practice. Founder and MD of Accotax, an ICAEW, ACCA and AAT regulated London practice that has served over 5,000 clients, and founder of Remindoo. Guidance is general; check current GOV.UK and professional body guidance for your firm.
What UK practices say about Remindoo
Read all reviews on Trustpilot“With Remindoo, everything from the first enquiry to onboarding and ongoing client management is tracked in one place… It saves us hours and gives me, as a practice owner, complete visibility of where the firm stands.”
“The biggest benefit is having clients, tasks, deadlines, workflows, proposals and communication all organised in one place.”
“During my trial, the team were absolutely amazing. They helped onboard my clients, set up my settings and made sure everything was ready for me to use… they made the whole process completely stress-free.”
“It brings client information, tasks, recurring deadlines, workflows and reminders together in one place, giving us much better visibility across the team.”
