Building Society: Banks Verge and Nat West

building society: And while some cash Isa rates at the big banks verge on the laughably bad we're looking at you, Nat West and Santander you really can find 26% a year, guaranteed and protected, from a building society, according to The Guardian. Read on to find out what's best for your money. Every year individuals can put 20,000 into an individual savings account but the deadline for doing so is 5 April just 27 days away. Lifetime Isa26.35% interest This is easily the best value government-approved Isa to buy, but also one that is littered with catches. It only pays about 1% interest, but the government bonus is worth 25%, so that makes a tasty 26% over the year. The idea is that you save up to 4,000 a year, and the government then tops it up with a 1,000 bonus. (news.financializer.com). As reported in the news.