(1) Subject to the provisions of paragraphs (2) and (3) of this regulation, where on or after the date on which she attained pensionable age a woman was a married woman by virtue of a polygamous marriage and either—
(a) throughout a day, falling on or after the date on which both she and her spouse have attained pensionable age and in respect of which neither of them has an entitlement to a Category A or Category B retirement pension which is deferred , that marriage was in fact monogamous, or
(b) throughout the day on which her spouse died that marriage was in fact monogamous,
that marriage, whether or not it has at all times been or continues to be in fact monogamous, shall, for the purposes of determining her right to and the rate of a retirement pension of any category under the Social Security Act be treated as having the same consequences as a monogamous marriage from and including the date on which she attained pensionable age or, if the marriage was contracted after that date, from and including the date of the marriage.
(2) Paragraph (1) of this regulation shall not operate so as to entitle a woman to a retirement pension for any period before the first such day as is referred to in sub-paragraph (a) of that paragraph or, in a case where that sub-paragraph does not apply, the day referred to in sub-paragraph (b) of that paragraph.
(3) Where the marriage of a woman is a polygamous marriage which was contracted—
(a) before she attained pensionable age and—
(i) was not in fact monogamous when she attained that age, but
(ii) became in fact monogamous on a date after she attained that age; or
(b) on or after the day on which she attained pensionable age and—
(i) was not in fact monogamous when it was contracted, but
(ii) became in fact monogamous on a date after it was contracted;
that marriage shall be treated as having the same consequences as a monogamous marriage for the purposes of section 29(10) of the Social Security Act (increase of Category B retirement pension in certain circumstances) only with effect from the date referred to in sub-paragraph (a)(ii) or, as the case may be, sub-paragraph (b)(ii) of this paragraph.
(4) In a case where section 28(3) of and Schedule 7 to the Social Security Act (retirement pension for widows who were widowed before attaining pensionable age) or regulation 4 of the Social Security (Benefit) (Married Women and Widows Special Provisions) Regulations 1974 (retirement pension for women whose marriages have been dissolved) applies to a woman and the relevant marriage for the purposes of that section and Schedule or that regulation was a polygamous marriage and throughout the day on which either—
(a) her marriage was dissolved, or
(b) her spouse died,
that marriage was in fact monogamous, that polygamous marriage shall, for those purposes, notwithstanding that it has not at all times been in fact monogamous, be treated as having the same consequences as if it had been a monogamous marriage.
(5) Where a woman is a married woman by virtue of a polygamous marriage which is in fact monogamous on the date from which she becomes entitled to a Category D retirement pension under section 39(1)(c) of the Social Security Act (retirement pensions for persons over age 80), that marriage, notwithstanding that it ceases to be in fact monogamous, shall, for the purpose of determining the rate of her Category D retirement pension, be treated as having the same consequences as a monogamous marriage.