CT600 company tax return filing in London: fixed fee, filed online by qualified accountants
We file your CT600 with HMRC for limited companies in the UK, with the accounts and tax computation attached in the format HMRC requires.
- Fixed fee, quoted up front
- Filed with HMRC
- 100% online, no office visits
★★★★★ Rated Excellent by 300+ clients
Get your fixed-fee quote
Tell us a little about your company. It takes about a minute.
Prefer to talk? 0203 4411-258 or freephone 0800 6441-258
What does CT600 tax return filing cost?
We quote a fixed fee for CT600 tax return filing before any work starts, based on your turnover and the state of your records. We handle the whole job online and file with HMRC.
- Best for
- Companies that need the CT600 filed with accounts and computations
- Fee
- Fixed fee, quoted up front
- Deadline
- Return: 12 months after the accounting period ends
- Filed with
- HMRC
- Service area
- Online, across the UK
Why directors choose us for CT600 tax return filing
Fixed fee
One price, agreed before we start.
Fully online
Share records and approve everything by email. No travelling, no posting paperwork.
Companies House and HMRC
We handle both filings together so nothing falls between the cracks.
Deadline reminders
We diarise your accounts, tax and confirmation statement dates.
Free eligibility check
Not sure you qualify? Our calculators tell you in a minute.
Rated Excellent
Rated 4.9 on Google by 300+ clients.
CT600 filing for UK limited companies
The CT600 is the company tax return form. It is filed online and has to be accompanied by the full statutory accounts and a tax computation in iXBRL format. Filing the CT600 with HMRC is a separate duty from filing accounts at Companies House, even though most companies deal with both in the same week.
What is included
- CT600 and any supplementary pages completed
- Accounts and computations tagged in iXBRL
- Filing through HMRC-recognised software, with the acknowledgement saved
- Payment reference and deadline explained
- Amendments handled if HMRC raises a query
How to file a CT600 online
- 1
Send your records and the accounting period dates.
- 2
We prepare the computation and the return.
- 3
You approve it online.
- 4
We file with HMRC and send you the acknowledgement.
CT600 deadlines for UK directors
Accounts
Due at Companies House 9 months after your year end.
Tax return
CT600 due at HMRC 12 months after your accounting period ends.
Tax payment
Corporation Tax is due 9 months and 1 day after your year end.
Confirmation statement
At least every 12 months, filed within 14 days of your review period ending.
Full filing deadlines guide · Late filing penalties · Eligibility calculator
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Ready for CT600 tax return filing?
Fixed fee, quoted up front. Filed with HMRC. 100% online.
What the CT600 is
The CT600 is the Company Tax Return that reports your profits to HMRC. It is due 12 months after your accounting period ends, while the Corporation Tax payment is due nine months and one day after. Late filing costs £100, with further penalties if it stays outstanding.
Corporation Tax rates
For the 2026/27 tax year, profits up to £50,000 are taxed at 19% and profits over £250,000 at 25%, with marginal relief between. Read marginal relief explained and the CT600 explained.
File your accounts See your instant price
More questions about this service
Do I file the CT600 with my accounts?
HMRC needs full accounts with it. We prepare both together.
When do I pay Corporation Tax?
Nine months and one day after the period end.
Is a CT600 needed if there are no profits?
Yes, if HMRC has issued a notice to deliver a return.
How much does CT600 filing cost?
It is included in our fixed accounts fee. We confirm any standalone price first.
Frequently asked questions
Do I need a CT600 if the company made a loss?
Yes, if HMRC has issued a notice to deliver a return. Filing also lets you carry the loss forward against future profits.
What happens if the CT600 is late?
An automatic £100 penalty applies if it is up to three months late, a further £100 after that, and tax-geared penalties follow if it is six months late.
Do you work with companies across the UK?
Yes. Everything is online, so we work with limited companies in England, Scotland and Wales. We are based in Morden, south London.
CT600 tax return filing near you
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