The offset mortgage allows borrowers to use savings to access a cheaper mortgage rate, whilst still having the ability to access the savings when necessary.

A minimum of £100 is needed to open the savings account and withdrawals are allowed without penalty or having to give notice. However, the account does not earn interest.

Family members of the borrower will also be to contribute to the savings account.

The mortgage is available to home buyers and remortgage customers and the mutual said each application would be considered on its own merit.

Keith Barber, director of business development at the Family Building Society, said many modern borrowers needed a more flexible product.

“It should be great for the self-employed, who have to keep money for tax aside during the year, and can struggle to get through the computer based credit assessments of some of the larger providers,” he said.

“We believe that linking a mortgage to savings accounts is an excellent way to help the self-employed or families, in particular, make more efficient use of money held in their savings accounts.

“So it can also be a great help to younger borrowers whose families have savings and want to help them without necessarily giving them cash outright.”