http://www.legislation.gov.uk/ukpga/1999/30/section/51Welfare Reform and Pensions Act 1999An Act to make provision about pensions and social security; to make provision for reducing under-occupation of dwellings by housing benefit claimants; to authorise certain expenditure by the Secretary of State having responsibility for social security; and for connected purposes.1999-11-16texttext/xmlenStatute Law Database2026-08-06Expert Participation2026-07-01 Part IVChapter II511In this Chapter—“shareable state scheme rights”, and related expressions, have the meaning given by section 47;“tax year” has the meaning given by section 122(1) of the Contributions and Benefits Act.2For the purposes of this Chapter—aa person is in the old state pension system if the person reached pensionable age before 6 April 2016 (or would have done so if the person had lived until pensionable age), andba person is in the new state pension system if the person reached pensionable age on or after 6 April 2016 (or will do so if the person lives until pensionable age).S. 51 wholly in force at 1.12.2000; s. 51 in force for certain purposes at Royal Assent see s. 89(1); s. 51 in force at 1.12.2000 insofar as not already in force by S.I. 2000/1047, art. 2(2)(d), Sch. Pt. IVPt. IV Ch. II modified (6.4.2016) by The Social Security (Northern Ireland Reciprocal Arrangements) Regulations 2016 (S.I. 2016/287), regs. 1, 2(2)(e)(ii), Sch.Pts. I-IV: power to modify conferred (26.11.2008) by Pensions Act 2008 (c. 30), ss. 146(2)(c), 149(2)S. 51: renumbered as s. 51(1) (6.4.2016 unless brought into force earlier by an order under s. 56(1) of the amending Act) by Pensions Act 2014 (c. 19), s. 56(4), Sch. 11 para. 14(2)Pts. I-IV: power to modify conferred (6.4.2006) by Pensions Act 2004 (c. 35), ss. 321(1)(d), 322(1); S.I. 2006/560, art. 2(3), Sch. Pt. 3S. 51(2) inserted (6.4.2016 unless brought into force earlier by an order under s. 56(1) of the amending Act) by Pensions Act 2014 (c. 19), s. 56(4), Sch. 11 para. 14(4)Words in s. 51 substituted (6.4.2016 unless brought into force earlier by an order under s. 56(1) of the amending Act) by Pensions Act 2014 (c. 19), s. 56(4), Sch. 11 para. 14(3)Pts. I-IV modified (6.4.2006) by Pensions Act 2004 (c. 35), ss. 254(3)(c), 322(1) (with s. 313); S.I. 2006/560, art. 2(3), Sch. Pt. 3