The first six months of the year saw the Yorkshire Building Society increase its core operating profit by 7.8%, to a total of £115.9m.
However, profit before tax was £111.2m, a 5% fall on June 2014.
During the same period, the UK’s second-largest building society increased mortgage balances by more than £600m and helped 3,386 first-time buyers to get on the housing ladder.
Chris Pilling, Yorkshire Building Society Group’s chief executive, said: “I’m pleased Yorkshire Building Society Group’s robust financial strength has once again been demonstrated through our performance in the first six months of 2015.
“We have continued to deliver on the goals and aims that our organisation was originally established to achieve, which we remain true to today – helping people to become homeowners and save for their futures. We have performed well in our core business areas, completing 15,430 mortgages and opening more than 85,000 savings accounts.
“Our healthy financial position allows us to offer borrowers some of the most competitive rates in the market. We were proud that in the first six months of this year, we helped 3,386 people take a step on to the housing ladder, with two in five of our house purchase mortgages provided to first-time buyers.
“But this level of lending can only continue if we can retain our profits and reinvest them back into our business. The Government’s proposal to introduce a bank surcharge of 8% on all banking services organisations’ profits over £25m will unfairly hit the six largest building societies, with these institutions paying about a third of the additional £1.7bn expected to be raised over five years.
“As the six largest building societies were responsible for 50% of the UK’s net mortgage lending in 2014, a tax which could impact our ability to fund growth in lending could have significant consequences for the UK mortgage market. As well as funding lending, we also use retained profit to invest in the business and to provide savers with overall returns that beat the market average.”