If you run a Limited Company in the UK, you’ll know Corporation Tax is one of those non-negotiables. You need to be aware of it, keep on top of your deadlines, and pay what you owe. 

Now and then, you may also need to get in touch with HMRC. And when that happens, knowing where to send things or who to call makes life a lot easier.

This guide walks you through how to contact HMRC about Corporation Tax, including the correct address, helplines, online tools, and how your accountant (like Crunch) can handle it all for you.

When to contact HMRC

Most companies can manage their Corporation Tax entirely online, especially if they use good software or an accountant. But there are situations where it makes sense to contact HMRC directly.

You might need to ask about a penalty, dispute a tax bill, change your accounting period, or chase a refund. If your company has just been formed and you haven’t received your Corporation Tax UTR yet, it’s worth checking in too.

It’s also important to let HMRC know if your company details change, like your registered address, or if you’re closing the business and need to sort out final Corporation Tax matters.

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The HMRC Corporation Tax address

When you need to send something to HMRC in the post and haven’t been given a specific address, use this:

Corporation Tax Services
HM Revenue and Customs
BX9 1AX
United Kingdom

This is a central mail-handling location rather than a physical office. If you use it, make sure your letter includes your 10-digit Corporation Tax Unique Taxpayer Reference (UTR), your company name and registration number, and any reference shown on previous HMRC correspondence. It helps HMRC identify your company and deal with your query more quickly.

If you’re responding to a letter, check the return address on it as this may be different. If another address is listed, be sure to check that the letter you have received is genuine before sending off any details.

HMRC has a list of recent letters sent for you to compare yours too. If you’d like more information on how to identify scam HMRC letters, we’d recommend checking out our article, “A comprehensive guide to identifying and dealing with HMRC scam letters.”

What about forms?

Depending on your query, HMRC might ask you to complete or refer to a specific form. Common ones include:

• CT600 – the main Corporation Tax return
  
  
• CT41G – for newly formed companies
  
  
• R38 – to claim a refund
  
  
• 64-8 – to authorise an accountant or agent (like Crunch)

Most of these are available to download or complete online.

How long does HMRC take to reply?

If you’re posting a letter to HMRC’s Corporation Tax address, they aim to reply within 15 working days. However, that can stretch during busy periods. Refunds and penalty appeals can take a few weeks to process, and more complex queries may take even longer.

HMRC do offer a free online tool which allows you to check when you should expect a reply from HMRC. It’s pretty useful to give you an estimate of when you should hear by. 

It’s a good idea to send important documents via recorded delivery and keep a copy for your records, just in case.

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Contacting HMRC through other means

Sometimes, sending a letter just isn’t enough. You may need to get in touch more quickly or have questions that require a conversation. Luckily, HMRC offers several other ways to contact them, including phone lines, online services, and more.

Calling HMRC

If you’d rather speak to someone, HMRC has a dedicated Corporation Tax helpline:

UK: 0300 200 3410
From abroad: +44 151 268 0571
Textphone: 0300 200 3411
Opening hours: Monday to Friday, 8am to 6pm (closed weekends and bank holidays)

Make sure you have your UTR and company details to hand when you call. Wondering where you can find your company UTR number? Check out our guide ‘“How to find and use your company UTR number?” for more information.

Lines are usually quieter mid-week and in the afternoons.

When to call HMRC

Lines tend to be less busy during the middle of the week, especially in the afternoons, so calling then can mean shorter wait times and quicker answers. Avoid Mondays and Fridays if you can, as those days are usually the busiest.

Online options for contacting HMRC

Before picking up the phone or sending a letter, it’s worth checking if you can do what you need online. You can log into your Corporation Tax account to file your return, check deadlines, view your account history, send messages to HMRC, or make a payment.

There’s sometimes a webchat feature available too, which can be quicker for basic questions.

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Can your accountant deal with HMRC?

Yes, and in most cases, they probably should. Sorting out Corporation Tax queries can be time-consuming and fiddly, especially if you’re not used to HMRC’s systems or processes.

When you use an accountancy service like Crunch, you don’t have to go it alone. Once you’ve granted us authority to act on your behalf (usually through your Government Gateway or a quick form), we can speak to HMRC directly for you. That covers everything from submitting your CT600 and chasing refunds to appealing penalties or setting up payment plans.

Even better, Crunch clients can get access to Crunch Protect, an optional add-on that gives you extra peace of mind. If HMRC ever launches a tax investigation into your company, Crunch Protect covers our time and costs in dealing with it, which could otherwise run into the thousands. It’s a bit like having a legal insurance policy for your business finances.

You can find out more about Crunch Protect here, or read how it works in practice in our Knowledge article.

Staying on top of it all

Corporation Tax might not be the most exciting part of running your Limited Company, but staying on top of it is essential to avoid fines or unexpected bills. Whether you need to send paperwork, correct an error, or appeal a penalty, there’s support available. Both from HMRC and from your accountant.

If you’re a Crunch client, you’ve got expert help in your corner every step of the way. And if you want to take your protection a step further, Crunch Protect can give you peace of mind in case HMRC ever comes knocking with questions or investigations.

Keep this guide handy so you know exactly where to send your letters, who to call, and when it’s best to let your accountant step in. Staying organised and informed means you can focus on what really matters, running your business with confidence.

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