These Regulations amend the Social Security (Contributions) Regulations 2001 (S.I. 2001/1004) (“the principal Regulations”) by modifying the way in which the liability of partners in AIFM firms for Class 4 contributions is determined. The amendments are made in connection with sections 863H to 863L of the Income Tax (Trading and Other Income) Act 2005 (c. 5) (“ITTOIA 2005”) (inserted by paragraph 15 of Schedule 17 to the Finance Act 2014 (c. 26)), which make special provision for determining the income tax liability for profits of partners in AIFM firms where those profits are deferred in line with regulatory requirements in connection with the Alternative Investment Fund Managers Directive (2011/61/EU).