Key takeaways
- The HMRC Corporation Tax helpline number is 0300 200 3410, or +44 151 268 0571 from outside the UK.
- The Corporation Tax helpline is open Monday to Friday, 8am to 6pm, and HMRC says it is least busy between 8:30am and 11am.
- You need your company's 10-digit Unique Taxpayer Reference, and HMRC advisers cannot give it to you over the phone.
- If your company cannot pay Corporation Tax on time, call the payment problems line on 0300 200 3840.
- HMRC's busiest period for Corporation Tax returns runs from December to April.
- Companies with profits up to £1.5 million must pay Corporation Tax 9 months and 1 day after the end of the accounting period.
- A Company Tax Return filed 1 day late gets a £200 penalty, rising to £1,000 if it is late 3 times in a row.
The HMRC Corporation Tax helpline is 0300 200 3410, open Monday to Friday, 8am to 6pm, and closed on bank holidays. HMRC says the line is least busy between 8:30am and 11am. Have your company’s 10-digit Unique Taxpayer Reference ready, because advisers cannot give it to you over the phone.
Which Corporation Tax number should you call?
General queries and payment problems use different numbers. These are the numbers on GOV.UK, checked on 6 November 2026.
| Query | Number | Notes |
|---|---|---|
| General Corporation Tax | 0300 200 3410 | Payments and repayments |
| Cannot pay on time | 0300 200 3840 | Payment problems line |
| Login and error messages | 0300 200 3600 | Online services helpdesk |
| Outside the UK | +44 151 268 0571 | Same hours |
All four lines open Monday to Friday, 8am to 6pm. Large businesses should contact their Customer Compliance Manager instead of the helpline.
The Corporation Tax general enquiries page was last updated on 6 October 2026, when HMRC added guidance on multiple or composite CHAPS payments. For other taxes, see our list of HMRC telephone numbers.
What the Corporation Tax helpline covers
The general line handles Corporation Tax enquiries, including payments and repayments. HMRC’s digital assistant also answers questions on four topics.
- Accounting periods
- Changing business details
- Corporation Tax repayments
- Paying Corporation Tax
If the digital assistant cannot help, you can ask to be passed to an adviser, if one is available.
What to have ready before you call
The one thing HMRC insists on is the company’s 10-digit UTR. It appears on HMRC letters and in the company’s online account. If you have lost it, request a copy; see how to find your UTR.
Use this checklist.
- The company’s 10-digit UTR
- The accounting period the query is about
- The 17-character payment reference, for payment queries
- The date and amount of any payment, and how you paid
- Any HMRC letter or penalty notice
If you are replying to a letter, HMRC says to use the address on that letter rather than the general one.
How to get through faster
Call between 8:30am and 11am, when HMRC says Corporation Tax lines are least busy. Avoid December to April if you can, because HMRC names it as the peak period for Corporation Tax returns.
HMRC does not publish a wait time for the Corporation Tax line alone. Its performance data, published on 8 October 2026, gives figures across all helplines.
| Month (2026) | Average wait | Calls over 10 minutes |
|---|---|---|
| June | 11:46 | 50.0% |
| July | 9:38 | 40.3% |
| August | 8:20 | 34.8% |
Our guide to the best time to call HMRC covers busy days and months.
Calls you may not need to make
HMRC asks callers not to chase some things by phone. Check these first.
- A payment that has not shown. Allow 3 working days for an electronic payment to reach HMRC. If you must pay again, wait 3 working days and use the same reference.
- A loss carry-back repayment. Do not send an amended return or a duplicate written claim; HMRC says resubmitting can slow things down.
- Several companies paying by CHAPS. Since 6 October 2026, GOV.UK has a form for one CHAPS payment covering more than one company in the same accounting period.
Key Corporation Tax deadlines
These deadlines come from the GOV.UK pages on paying Corporation Tax and Company Tax Returns.
| What | Deadline |
|---|---|
| Pay (profits up to £1.5 million) | 9 months and 1 day after the period ends |
| Pay (profits over £1.5 million) | Quarterly instalments |
| File the Company Tax Return | 12 months after the period ends |
Late filing penalties are £200 at 1 day, another £200 at 3 months, then 10% of unpaid tax at 6 months and another 10% at 12 months. If a return is late 3 times in a row, the £200 penalties rise to £1,000 each. Our Corporation Tax payment deadlines guide explains the rules, and our Corporation Tax calculator estimates the bill.
Writing to HMRC about Corporation Tax
The postal address is Corporation Tax Services, HM Revenue and Customs, BX9 1AX, United Kingdom. Put the company’s UTR in the letter and on the first page of any documents.
Which applies to you?
- If the company cannot pay by the due date, call 0300 200 3840 before the deadline.
- If you cannot sign in to file the CT600, call 0300 200 3600.
- If you are an agent, note that HMRC’s agent dedicated line covers Self Assessment and PAYE for individuals; GOV.UK lists no agent line for Corporation Tax.
- For anything else, call 0300 200 3410 between 8:30am and 11am.
Frequently asked questions
What is the HMRC Corporation Tax helpline number?
The number is 0300 200 3410. From outside the UK, call +44 151 268 0571.
What are the Corporation Tax helpline opening hours?
It is open Monday to Friday, 8am to 6pm, and is closed on bank holidays.
Can HMRC give me my company’s UTR over the phone?
No. HMRC says its advisers cannot give you the UTR over the phone, but you can request a copy.
What is the best time to call the Corporation Tax helpline?
HMRC says the lines are least busy between 8:30am and 11am. December to April is the busiest period.
Who do I call if my company cannot pay its Corporation Tax?
Call the Corporation Tax payment problems line on 0300 200 3840, Monday to Friday, 8am to 6pm.
Sources
Rates, thresholds and rules in this guide were checked against HMRC and GOV.UK guidance on 6 November 2026. Tax rules change, so check the current position on GOV.UK or with a qualified adviser before acting. This guide is general information, not personal advice.