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If HMRC needs to contact you about anything confidential they’ll reply by phone or post.


  • Telephone: 0300 123 2326
  • Fax: 03000 533 404

Call HMRC for help with IR35 enquiries.

Find out about call charges

Opening times:

8.30am to 5pm, Monday to Thursday
8.30am to 4.30pm Friday

Closed weekends and bank holidays


Write to HMRC for help with IR35 enquiries.

HM Revenue and Customs - IR35 Customer Service Unit

Ground Floor North Princess House Cliftonville Road, Northampton NN1 5AE United Kingdom

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Don’t include personal or financial information, eg your National Insurance number or credit card details.