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If HMRC reply to your enquiry by email the information is not secure. If they need to contact you about anything confidential, they will reply by post or telephone.


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

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


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.