Capital Gains Tax Sir Brandon Rhys Williams asked the Chancellor of the Exchequer what is his estimate of the additional revenue in 1987–88 of taxing all real capital gains, after allowing for inflation, at 40 per cent. but with separate taxation of husband and wife, excluding gains arising on disposals of a person's only or main residence. Mr. Norman Lamont The present yield of capital gains tax would be reduced by about one-third.