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Find out when you can expect to receive a reply from HMRC to a query or request you've made.
Find recognised commercial software suppliers and software you can use to file your Company Tax Return and any supplementary pages online.
Overview You should file your Company Tax Return online using commercial…
Use this form if you are a sole trader, company or organisation to get a certificate of residence or letter of confirmation so you do not pay tax twice on foreign income.
Find and use tools and calculators that will help you work out your tax.
Find out how to file your accounts and Company Tax Return if you previously used the HMRC online service that closed on 31 March 2026.
You can reduce your Corporation Tax bill through Marginal Relief from 1 April 2023 if your company’s profits are lower than £250,000.
Find out what information you need to send HMRC before you make a claim for R&D Corporation Tax relief.
How to complete your CT600 Company Tax Return form for Corporation Tax and what information you need to include.
How to work out payments and when you should make them if your company’s annual taxable profits are between £1.5 million and £20 million.
If you're a close company or a tax agent, find out how to claim relief for loans that have been repaid, released, or written off.
Find out about being 'active', trading and non-trading, and being dormant if you’re a new or existing company or organisation.
Check if you need to submit a claim notification form before you claim R&D Corporation Tax relief, what information you’ll need to provide and how to send it.
Find out what R&D tax relief is and if your project qualifies for Corporation Tax relief.
Use the online tool throughout a check to guide you through each stage and to access the support available.
Find out if you can claim under the merged R&D expenditure credit (RDEC) scheme or enhanced R&D intensive support (ERIS) for accounting periods beginning on or after 1 April 2024.
How to work out and claim Corporation Tax relief on trading losses.
Find out why penalty determinations are issued and what to do if you receive one.
Find out about PAYE, Income Tax and National Insurance contributions rules when overseas workers come to the UK for short periods.
Find out how to work out payments and when you should make them if your company’s annual taxable profits are over £20 million.
Use form WT1 if you cannot send your Company Tax Return online because of an IT problem with HMRC online services.
Do not include personal or financial information like your National Insurance number or credit card details.
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