11. This Arrangement shall come into force on the date on which the last of all such things shall have been done in the United Kingdom and Guernsey as are necessary to give the Arrangement the force of law in the United Kingdom and Guernsey respectively, and shall thereupon have effect:—
(a)In the United Kingdom:
as respects income tax, for any year of assessment beginning on or after the 6th April, 1951;
as respects surtax for any year of assessment beginning on or after the 6th April, 1950; and
as respects profits tax, in respect of the following profits—
(i)profits arising in any chargeable accounting period beginning on or after the 1st April, 1951;
(ii)profits attributable to so much of any chargeable accounting period falling partly before and partly after that date as falls after that date;
(iii)profits not so arising or attributable by reference to which income tax is, or but for the present Arrangement would be, chargeable for any year of assessment beginning on or after the 6th April, 1951;
(b)In Guernsey:
as respects income tax and super tax, for any years of charge beginning on the first day of January, 1951, and subsequent year.