By Jonathan Davies
Nationwide has said its lending may be affected by tax changes that could cost it £300 million over the next five years.
The lender said changes announced by the Chancellor George Osborne in the Summer Budget would cost the equivalent of the capital needed to fund £10 billion worth of lending.
The Chancellor announced that the annual levy paid by banks on their balance sheet would be reduced from 0.21% to 0.1%. But a new 8% surcharge on profits will be introduced instead. That is expected to result in the £300m cost to Nationwide.
In the three months to the end of June, Nationwide's profits rose from £253m to £379m.
Chief executive Graham Beale said: "Nationwide accounted for more than a quarter of total net lending to the UK housing market."
Mortgage lending increased 17.2% to £6.8bn, with net lending rising 23.5% to £2.1bn.
Mr Beale claims that the 8% surcharge will benefit the UK's big, international banks, but will have a detrimental affect on building societies.
He said: "This represents a missed opportunity to support diversity by acknowledging that building societies are different to banks and to recognise the contribution Nationwide and other mutuals make by lending to the UK economy, and the housing market in particular."