HC Deb 27 July 1984 vol 64 c864W
Mr. Gordon Brown

asked the Chancellor of the Exchequer what is his estimate of the effect on revenue accruing to the Treasury in 1984–85 of the tax concessions made since 1979 in the following areas:(a) investment income surcharge, (b) reduction in the top rate of income tax, (c) changes in capital gains tax and (d) reductions in corporation tax.

Mr. Moore

Estimates are given of the increase in revenue in respect of 1984–85 if 1978–79 rates, reliefs, thresholds and bands—the latter after indexation by the movement in the RPI—were to be imposed in place of those of the 1984 Finance Bill, and if there were no consequent change in economic performance:

£ million
Investment income surcharge (IIS) 560
Rates of income tax above the basic rate (excluding IIS) 950
Capital gains tax 150

Any estimate relating to corporation tax must be regarded as highly tentative, given the significance of "tax exhaustion" during this period and the likelihood that companies' activities would alter under a different tax regime. The corresponding increase of receipts in 1984–85 might have been between £½ billion and £1 billion.