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Deadlines & compliance
Corporation Tax and CT600 Deadline Tracking
Two different corporation tax dates per client, tracked correctly and separately.
Built by a practising Chartered Accountant · Unlimited users · Free for 60 days
Detailed task creation
Set priority, assignee and deadline on every job.
- Premier Books Consultancy
- Cranleys Chartered Accountants
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- Auditax International
- RS
Quick answer
CT600 deadline tracking means recording two separate dates for every limited company client: the corporation tax payment deadline (9 months and 1 day after the accounting period ends) and the CT600 filing deadline (12 months after the accounting period ends). Treating them as one date causes payments to be missed even when the return is filed on time.
What is CT600 deadline tracking and why does it matter for UK practices?
It's the practice of tracking corporation tax payment and CT600 filing as two distinct deadlines with different timing, rather than treating 'corporation tax' as a single date, which is a common and costly simplification.
Corporation tax must be paid 9 months and 1 day after the end of the accounting period, while the CT600 return itself doesn't need to be filed until 12 months after the accounting period ends. That three-month gap between payment and filing is where confusion, and missed payments, most often happen.
| Obligation | Deadline |
|---|---|
| Pay corporation tax | 9 months and 1 day after the accounting period ends |
| File CT600 return | 12 months after the accounting period ends |
Why does CT600 deadline tracking keep going wrong?
Payment and filing treated as one date
A tracker with a single 'corporation tax deadline' column often defaults to the later filing date, missing the earlier payment obligation entirely.
Payment due before the return is finished
Because payment falls before the filing deadline, the tax liability has to be estimated and paid before final figures are confirmed, which some trackers don't account for at all.
No link to the accounts preparation timeline
Corporation tax dates run from the same accounting period as the annual accounts, but if they're tracked separately, the connection between the two can be missed.
Interest accrues quietly on late payment
Because the payment deadline isn't as widely known as the filing deadline, a late payment can go unnoticed until interest has already built up.
Multiple accounting periods per company aren't handled correctly
A long or short accounting period can create two CT600 periods in a single calendar year, which a simple annual tracker may not capture correctly.
What does a missed corporation tax payment or CT600 deadline cost an accounting firm?
HMRC charges interest on corporation tax paid late, and separate penalties apply for a late CT600 return, so treating the two obligations as one increases the risk of paying both a penalty and accruing avoidable interest.
The confusion between payment and filing dates is a common source of client frustration, since clients often assume 'we've filed' means 'we've paid', when the two are entirely separate obligations with different timing.
How do you track corporation tax and CT600 deadlines correctly? Step by step
- 1
Record both deadlines separately for every client
Set up the payment deadline and the CT600 filing deadline as two distinct dates, not one combined 'corporation tax' entry.
- 2
Calculate an estimated liability ahead of the payment deadline
Since payment is due before filing, prepare an estimate early enough to give the client time to fund the payment.
- 3
Link both dates to the underlying accounting period
Tie corporation tax deadlines to the same accounting period used for the annual accounts, so a change in year end updates both automatically.
- 4
Set reminders ahead of the payment deadline specifically
Don't rely on the filing deadline reminder to also cover payment, since it falls three months later.
- 5
Assign a named owner for the CT600 return itself
Filing still needs to happen within 12 months, even once payment has been made.
- 6
Check for short or long accounting periods when a client's year end changes
A change in year end partway through a period can create two CT600 obligations that need tracking individually.
- 7
Confirm payment has cleared, not just been instructed
Record confirmation of payment separately from the instruction to pay, to catch any processing delays.
How does Remindoo help track corporation tax and CT600 deadlines?
Remindoo lets you create separate detailed tasks for the corporation tax payment deadline and the CT600 filing deadline against the same client, rather than collapsing them into a single date that hides the three-month gap between the two. Trigger dates let both tasks be generated from the client's accounting period end, so if a year end changes, the dates tied to it can be reviewed and updated together rather than drifting out of sync. Automated reminders are set independently for each deadline, prompting for the payment estimate well before the 9-month-and-1-day date and separately for the CT600 filing itself. Recurring tasks carry this structure forward automatically for the next accounting period, so the distinction between payment and filing doesn't need to be rebuilt by hand every year.
Detailed task creation
Set priority, assignee and deadline on every job.
See featureTrigger dates
Start work from key filing or internal dates.
See featureAutomated reminders
Timely prompts before work becomes urgent.
See featureRecurring tasks
Repeat work is created automatically on schedule.
See featureTask card and detail view
Attachments, subtasks and notes on every task.
See featureSpreadsheets vs Remindoo: what changes?
| Area | Spreadsheets & email | With Remindoo |
|---|---|---|
| Payment vs filing | One combined 'corporation tax' date | Two separate tasks with their own deadlines |
| Liability estimate | Prepared late or skipped | Reminded ahead of the payment deadline |
| Link to accounting period | Manually cross-checked, if at all | Tied to the same trigger date |
| Recurrence | Rebuilt manually each period | Carried forward automatically |
| Short/long periods | Easy to miss a second CT600 obligation | Reviewed explicitly when the year end changes |
See it with your own clients
A 30-minute walkthrough using your services and deadlines.
Why does corporation tax need to be paid before the CT600 is filed?
Because the payment deadline falls at 9 months and 1 day after the accounting period ends, three months before the 12-month filing deadline, the liability has to be estimated from draft figures rather than waited on until the final return is complete.
Firms that prepare an early estimate as a standard step in year-end work avoid the payment deadline becoming an unplanned rush once accounts preparation catches up.
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Frequently asked questions
When is corporation tax due to be paid?
9 months and 1 day after the end of the accounting period, which is earlier than the CT600 filing deadline.
When must the CT600 return be filed?
12 months after the end of the accounting period, three months after the payment deadline.
Why are these two dates often confused?
Because both relate to 'corporation tax', it's easy to track them as a single date, which usually defaults to the later filing deadline and causes the earlier payment to be missed.
What happens with a short or long accounting period?
A change in year end can create two CT600 periods within a short span, each with its own payment and filing deadlines that need tracking individually.
Can Remindoo track payment and filing as separate tasks?
Yes, each can be set up as its own detailed task with its own deadline and reminders, rather than one combined date.
Is Remindoo free to try before committing?
Yes, it's free for 60 days with full functionality, enough to set up and test a corporation tax tracking structure for real clients.
Does Remindoo calculate or submit corporation tax?
No, Remindoo tracks the deadlines and manages the tasks and reminders around them; calculation and submission remain part of your existing tax process.
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Sources
Comparing options? Read our guide to accounting practice management software.
Last updated: . General guidance, not regulatory advice. Check with your professional body.
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.”
