F1The Treasury may with the concurrence of the Department make regulations modifying Parts I to V of this Act F2and Part III of the Social Security Contributions (Transfer of Functions, etc.) (Northern Ireland) Order 1999, and any provision of Part II of the Administration Act which replaces provisions of Part III of the 1975 Act, in such manner as F3the Treasury think proper, in their application to persons who are or have been outside Northern Ireland at any prescribed time or in any prescribed circumstances.