Mortgage Interest Tax Relief Mr. Woolmer asked the Chancellor of the Exchequer what revenue saving to the Exchequer is expected in a full year when mortgage interest tax relief is given by deduction at source instead of by tax allowance. Mr. Ridley [pursuant to his reply, 28 April 1982, c. 278]: There will be a small increase in expenditure in giving full relief to borrowers who at present do not get it through the tax system because their incomes are too low. This will be partly offset by revenue savings to give a net increase in the cost of mortgage relief in a full year, estimated at £5 million at 1982–83 levels of income, interest rates, and so on. There is unlikely, however, to be any net cost to public funds because this increase will be offset by the reduction in Inland Revenue staff costs.