Tax Survey in the UK

3.6. Corporation tax
Corporation tax is charged on the global profits of UK-resident companies, public
corporations and unincorporated associations. Firms not resident in the UK pay
corporation tax only on their UK profits. The profit on which corporation tax is
charged comprises income from trading, investment and capital gains. Trading losses
may be carried back for one year to be set against profits earned in that period or
carried forward indefinitely.7 The standard rate of corporation tax in 2003–04 is 30%,
with a reduced rate of 19% on profits under £300,000. For firms with profits between
£300,000 and £1,500,000, a system of relief operates, such that an effective marginal
rate of 32.75% is levied on profits in excess of £300,000. This acts to increase the
average tax rate gradually until it reaches 30%. A zero rate applies for profits up to
£10,000, with an effective marginal rate of 23.75% levied on profits between £10,000
and £50,000 to bring the average tax rate gradually up to 19%. Table 11 presents
marginal and average corporation tax rates.
Broadly speaking, current expenditure is deductible from taxable profits, while capital
expenditure is not. To allow for the depreciation of capital assets, however, firms can
claim capital allowances, which reduce taxable profits over several years by a
proportion of capital expenditure. Capital allowances may be claimed in the year that
they accrue, set against future profits, or carried back for up to three years. Different
classes of capital expenditure attract different capital allowances:
Expenditure on plant and machinery may be ‘written down’ on a 25%
declining-balance basis. A higher, 40%, allowance is available in the first year
for expenditure by small and medium-sized companies.
Expenditure on industrial buildings and hotels is written down on a straight-line
basis of 4% per year.
Expenditure on commercial buildings may not be written down at all.
Intangible assets expenditure is written down on a straight-line basis at either
the accounting depreciation rate or a rate of 4%, whichever the company
prefers.

…