Duplicate NI Number

Hello, my client has the same NI number as another person. He went through a process with HMRC about 10 years ago when he was told he’d be able to keep the NI No and the ‘intruder’ would have to apply for a new one. However, the intruder has continued to use it. The tax accounts are muddled so my client has the intruder’s pension income showing on his tax coding notice, gateway account and so on. Attempts to sort this out by phone are proving fruitless. Who can we write to (email or letter) to get this resolved?

Hi Rebecca,
I am sorry to hear of the problems your client is having. You should write to  the following address:
National Insurance Account Investigations
HM Revenue and Customs
National Insurance Contributions and Employer Office
BX9 1AN
Thank you.