NS&I has agreed to hold client letters of authority on file, meaning advisers will no longer have to supply one every time they request information.
These new services have been introduced in response to feedback from financial advisers.
Previously firms had to supply a new letter of authority, signed by the customer, every time they requested information but these will now be kept on file indefinitely.
As part of the changes, advisers will also be able to access to information about their clients’ NS&I holdings by phone after the government-backed provider upgraded its adviser helpline.
Previously, requests on clients' holdings could only be made by post and it could take up to two or three weeks for a response to be provided.
Andrew Pike, head of intermediary relationships at NS&I, said: "These new features of NS&I’s adviser helpline mean that NS&I is able to provide a faster and more comprehensive service to advice firms.
"We know that advisers often recommend NS&I products and are very supportive of our unique security guarantee, but they also tell us we could make life easier for them when contacting us.
"Therefore we expect these new enhancements will make a real difference."
There will be a new agreement between NS&I and each advice firm who wishes to have access to information on their clients' NS&I holdings, which will form the legal relationship between NS&I and a financial advice firm, and protect the relationship between both parties and their mutual customers.
In addition, all staff in an advice firm will be able to have access to client information, as long as the firm has signed and supplied a terms of business agreement and the relevant letter of authority is in place.
Mike Pendergast, a financial adviser with Cheshire-based Zen Financial Services, said: "If you have a client with holdings in NS&I, a lot of the time they won't know how much they have got and which particular type of bond it is so this is a step in the right direction."