The purpose of the clause is to standardise the rules relating to the date at which corporation tax is payable. After a transitional period, corporation tax will, in all cases, be payable nine months after the end of the accounting period for which it is chargeable. As the hon. Member for Thurrock (Dr. McDonald) knows, there have been a number of publicised cases with potential tax avoidance in this area and that is one reason why the change has been made.