To merge your account(s), please write to us at NS&I, Sunderland SR43 2SB with a signed letter.

We no longer use our old Glasgow or Blackpool addresses, so please don't send anything there.

Please include information about all of your relevant holdings:

• your name
• your date of birth
• your home address
• your current NS&I number you use to log in

Details of your accounts or investments, if you know them:

• the type of investment (e.g. Premium Bonds)
• approximate start date
• amount invested
• your holder’s or customer number
• your account number
• your Bond numbers or Certificate numbers (you’ll find these numbers on your Bond records, certificates of investment or any other letters from us)

If you haven’t told us about a house move or a change in your marital status or name, please also include your previous name and address.

If the name and/or address is different on your old Bonds, please include your previous details as well.

The more details you can give when you write to us, the quicker we can deal with your request.

Don't forget to sign your letter. For your security, we can’t disclose or change personal information without the account holder’s signature(s).

If you are over 16 and the investment was made for you when you were a child, we might not have your signature on our records. In that case, your signature should be witnessed so we can transfer control of any investments to you. The witness must be aged 18 or over and must not be a member of your family. The witness must also sign the form.