20.—(1) Subject to subsection (3), a review of the rent under the tenancy of a dwelling may not occur—

(a) more frequently than once in each period of 12 months, nor

(b) in the period of 12 months beginning on the commencement of the tenancy.

(2) Subsection (1) has effect notwithstanding any provision to the contrary in the lease or tenancy agreement concerned.

(3) Subsection (1) does not apply despite the fact that a period of less than 12 months has elapsed from—

(a) the last review of the rent under the tenancy, or

(b) the commencement of the tenancy,

if, in that period—

(i) a substantial change F63[(within the meaning of subsection (5A) of section 19)] in the nature of the accommodation provided under the tenancy occurs, and

(ii) the rent under the tenancy, were it to be set immediately after that change, would, by virtue of that change, be different to what was the market rent for the tenancy at the time of that last review or the commencement of the tenancy, as the case may be.

F64[(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 F65[1 January 2025] and from that 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 F65[31 December 2024].]