25. (1) Section 20 of the Principal Act is amended by inserting the following subsections after subsection (3):

“(4) The references to ‘12 months’ in—

(a) paragraphs (a) and (b) of subsection (1), and

(b) subsection (3),

shall, for the duration of the relevant period, be construed as references to ‘24 months’.

(5) Subsections (4) and (6) shall cease to have effect on the day immediately before the fourth anniversary of the day on which section 25 of the Residential Tenancies (Amendment) Act 2015 came into operation and, on and from the first-mentioned day—

(a) paragraphs (a) and (b) of subsection (1), and

(b) subsection (3),

shall be read as if subsection (4) had not been enacted.

(6) In subsection (4), ‘relevant period’ means the period commencing on the day on which section 25 of the Residential Tenancies (Amendment) Act 2015 comes into operation and ending on the day immediately before the fourth anniversary of the day on which that section came into operation.”.

(2) In the case of a tenancy which commenced before the coming into operation of subsection (1), for the purposes of the amendments effected by that subsection, where—

(a) a period of 12 months, beginning on the commencement of the tenancy, has not elapsed before the day on which subsection (1) comes into operation, a review of rent under that tenancy may not occur until a period of 24 months, beginning on the commencement of the tenancy, has elapsed,

(b) a period of 12 months, beginning on the date of the commencement of the tenancy, has elapsed before the day on which subsection (1) comes into operation and a review of rent under section 20 of the Principal Act has not been carried out before that day, a review of rent may not occur until a period of 24 months, beginning on the commencement of the tenancy, has elapsed,

(c) a review of rent was carried out pursuant to section 20(3) of the Principal Act and that review of rent was the most recent review of rent carried out before the coming into operation of subsection (1), a review of rent may not occur until a period of 24 months, beginning on the date of that most recent review of rent, has elapsed, or

(d) one or more reviews of the rent under that tenancy has, or have, been carried out in accordance with section 20 of the Principal Act, a review of rent may not occur until a period of 24 months, beginning on the date of the most recent review of rent carried out before the coming into operation of subsection (1), has elapsed.

(3) The amendments effected by subsection (1) —

(a) shall not apply in respect of a review of rent under the tenancy of a dwelling carried out under section 20 of the Principal Act where a review of rent—

(i) is being carried out in accordance with that section before the day on which subsection (1) comes into operation, or

(ii) has been carried out in accordance with that section before the day on which subsection (1) comes into operation, pursuant to which a notice under section 22(2) of the Principal Act has been served on the tenant concerned before the day on which subsection (1) comes into operation,

and

(b) shall apply in respect of a review of rent under the tenancy of a dwelling carried out after the review of rent referred to in paragraph (a) during the period for which subsections (4) and (6) of section 20 of the Principal Act have effect.