Skipton Building Society said total group profit before tax rose to £104.7 million in the six months to June 30, up from £67 million at the same stage last year.
Group total assets increased by 4.9% since the year end to £22.1 billion.
The UK’s fourth largest building society said it increased its membership by 52,842 to 971,902.
Skipton broadened its wholesale funding base, issuing regulated public covered bonds and raising £400 million over a five year term.
Group gross mortgage lending fell to £1.8 billion from £2.4 billion at the same stage of 2017 with Skipton saying: “… the reduction in the period being due to the intensity of competition within the mortgage market, together with the impact of more stringent customer affordability criteria we introduced towards the end of 2017.”
Mortgage balances grew £457 million to £17 billion and savings balances grew £471 million to £15.4 billion.
Skipton CEO David Cutter said: “The first half of 2018 has seen another strong performance for Skipton, as we continue to support ourmembers in planning for their lives ahead.
“In the first half of this year, we have seen continued growth in our membership.
“This includes us having over 110,000 LISA customers as at 30 June 2018 as Skipton remains the only organisation to support younger savers by providing a cash LISA account.
“Total cash LISA balances amounted to £508.3m at 30 June 2018 and £99.0m in government bonuses were paid to LISA customers during the period, a fantastic benefit for this new cohort of younger savers.
“In doing so we are continuing to deliver on our 165-year-old founding mutual purpose of helping people save and buy their own homes.
“The Society’s performance in the first half of 2018 is pleasing, with sustainable growth in mortgage and savings balances, strong liquidity, and a growth in our net interest margin.
“We have continued to invest in our member offering, and Skipton is now one of the few financial services providers on the UK high street to offer full mortgage and financial advice video appointments.
“Called ‘Skipton Link’, this popular mortgages, investments and pensions service allows our members to link up via video from home or branch with any of our UK branches, Skipton’s head office or home-based financial advisers.
“As a mutual, we will continue re- investing in our business for the benefit of our members.”