The number of adults taking out Individual Savings Accounts (Isa) has fallen to its lowest level for ten years, according to official figures.
HM Revenue and Customs said there were 13m new accounts opened in 2014-15, down from 13.5m the year before.
The figure, the lowest since 2004-05, will be disappointing for the Treasury, which is trying to encourage more people to save.
It comes in spite of an increase in the amount savers can put in to an Isa.
In July last year the maximum subscription amount was increased to £15,000 for both cash and stocks-and-shares Isas.
The current limit is £15,240.
The accounts are free of both Income and Capital Gains Tax.
One reason for the fall may be that savings rates have been so low that being tax-free offers little extra advantage.
Indeed, a typical one year fixed-rate cash Isa offers a 1.75% return, while some one year savings bonds offer as much as 2%.
However Junior Isas, for those under 18, did prove more popular.
In 2014-15 there were 510,000 new accounts opened, up from 432,000 the year before.
Of savings already in Isas, 80% is held in cash, and 20% is in stocks and shares, according to the HM Revenue and Customs.
The average investment is £6,064.