(5) In this Article the term "nationals" means-
 (a) in relation to Norway, all Norwegian citizens and all juridical persons
 domiciled in Norway;
 (b) in relation to the United Kingdom, all British subjects and British-
 protected persons residing in the United Kingdom or any British territory
 to which the present Convention applies by reason of extension made
 under Article- XX, and all legal persons, partnerships and associations
 deriving their status as such from the law in force in any British territory
 to which the present Convention applies.
 (6) In this Article the term "taxation" means taxes of every kind and
description levied on behalf of any authority whatsoever.

 ARTICLE XX.
 (1) The present Convention may be extended, either in its entirety or with
modifications, to any territory for whose international relations the United
Kingdom is responsible and which imposes taxes substantially similar in charac-
ter to those which are the subject of the present Convention, and any such
extension shall take effect from such date and subject to such modifications and
conditions (including conditions as to termination) as may be specified and
agreed between the Contracting Parties in notes to be exchanged for this
purpose.
 (2) The termination in respect of Norway or the United Kingdom of the
present Convention under Article XXII shall, unless otherwise expressly agreed by
both Contracting Parties, terminate the application of the present Convention
to any territory to which the Convention has been extended under this Article.

 ARTICLE XXI.
 (1) The present Convention shall be ratified and the instruments of ratifica-
tion shall be exchanged at Oslo as soon as possible.
 (2) The present Convention shall enter into force upon the exchange of
ratifications and the foregoing provisions thereof shall have effect--
 (a) In the.United Kingdom:
 as respects income tax for any year of assessment beginning on or after
 6th April, 1950;
 as respects surtax for any year of assessment beginning on or after
 6th April, 1949; and
 as respects profits tax in respect of the following profits:-
 (i) profits arising in any chargeable accounting period beginning on
 or after 1st April, 1950;
 (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 Convention would be, chargeable for
 Iny year of assessment beginning on or after 6th April, 1950;
 (b) In Norway:. -
 for the taxable years beginning on op after 1st January, 1950.