Corporation Tax is levied on the profits of companies and certain unincorporated associations. For most companies the rate of corporation tax is 20% although higher rates are payable by businesses whose profits exceed £300,000 per annum.
Whilst some very large businesses pay corporation tax quarterly, most companies pay 9 months and 1 day after the end of their accounting period. So a company that makes up its accounts for the period 1 January 2011 to 31 December 2011 will need to pay its corporation tax no later than 1 October 2012.
Dividends paid or received by a company are excluded from the calculations of profits. So for example, a management consultant company with profits of £40,000 after deducting £60,000 dividends it has paid will pay corporation tax on £100,000 profits.