4.The Act makes provision about the rate at which corporation tax is charged on the profits of certain trades and activities of Northern Ireland companies, the Northern Ireland rate. The Northern Ireland Assembly may set that rate by resolution independently of the percentage at which the normal UK main rate is set. The provisions in this Act give details of what trades and activities fall within the scope of the Northern Ireland rate, if one is set. The rate will be applied to trading income only, with other sources of income remaining chargeable at the main rate of corporation tax.