16 Substitution of regulations 80 and 81 of the Housing Benefit Regulations 2006
For regulations 80 (calculation of weekly amounts) and 81 (rent free periods) substitute—

“80 Calculation of weekly amounts
1 A person’s entitlement to housing benefit in any benefit week shall be calculated in accordance with the following provisions of this regulation.
2 The weekly amount of a claimant’s eligible rent shall be—
(a) subject to paragraph (3), where rent is payable at intervals of one week or a multiple thereof, the amount of eligible rent payable weekly or, where it is payable at intervals of a multiple of a week, the amount determined by dividing the amount of eligible rent payable by the number equal to the number of weeks in respect of which it is payable; or
(b) subject to paragraph (3), where the rent is payable at intervals of a calendar month or multiples thereof, the amount determined by dividing the amount payable by the number equal to the number of calendar months in respect of which it is payable, multiplying by 12 and dividing by 52;
(c) subject to paragraph (3), where the rent is payable at intervals of a day or multiples thereof, the amount determined by dividing the amount payable by the number equal to the number of days in respect of which it is payable and multiplying by 7.
3 In a case—
(a) to which regulation 76(2) or (3) (date on which entitlement is to commence) applies, his eligible rent for the benefit week in which he becomes liable to make payments in respect of a dwelling which he occupies as his home shall be calculated by multiplying his daily rent by the number equal to the number of days in that benefit week for which he is liable to make such payments;
(b) where a change of circumstances takes effect in a benefit week under regulation 79(2A), (but is not a change described in sub-paragraph (c)(ii) of this regulation), (2B), (8) or (9) other than on the Monday of a benefit week then the claimant’s eligible rent for that benefit week shall be calculated by multiplying his daily rent by the appropriate number of days in that benefit week;
(c) where—
(i) the amount of eligible rent which the claimant is liable to pay in respect of a dwelling is altered and that change of circumstances takes effect under regulation 79(2); or
(ii) the claimant—
(aa) moves to a new dwelling occupied as the home,
(bb) he is not entitled to be treated, immediately after that move, as occupying two dwellings as his home or as occupying his former dwelling as his home, and
(cc) that change of circumstances takes effect under regulation 79(2A),
other than on the Monday of a benefit week, then the claimant’s eligible rent for that benefit week shall be calculated by multiplying his old and new daily rent by the number equal to the number of days in that week which relate respectively to the old and new amounts which he is liable to pay.
4 In the case of a claimant whose weekly eligible rent falls to be calculated in accordance with paragraph (3)(a) or (b) by reference to the daily rent in his case, his weekly applicable amount, weekly income, the weekly amount of any non-dependant deductions and the minimum amount payable in his case shall be calculated in the same manner as his weekly eligible rent by reference to the amounts determined in his case in accordance with Parts 5 to 8 (applicable amounts, income and capital, students and amount of benefit).
5 Where a change in the amount of a claimant’s applicable amount, income or non-dependant deductions falls to be taken into account in the same benefit week as a change in his eligible rent to which paragraph (3)(c) applies, it shall be taken into account in that week on a daily basis in the same manner and as if it had occurred on the same day as that change in his eligible rent.
6 In any case where a claimant has received an extended payment or an extended payment (severe disablement allowance and incapacity benefit), his entitlement shall be adjusted in such circumstances and by such amount as are prescribed in Part 3 of Schedule 7 or paragraph 9 of Schedule 8, as the case may be.
7 Any amount determined under these Regulations may, if it is appropriate, be rounded to the nearest whole penny by disregarding any amount less than half a penny and treating any amount of half a penny or more as a whole penny.
8 In this regulation “daily rent” shall mean the amount determined by dividing by 7 the amount determined under whichever sub-paragraph of paragraph (2) is appropriate in each case.
9 Where a claimant is entitled to benefit in respect of two (but not more than two) dwellings in accordance with regulation 7(6) his eligible rent shall be calculated in respect of each dwelling in accordance with this regulation.

81 Rent free periods
1 This regulation applies to a claimant for any period (referred to in this regulation as a rent free period) in, or in respect of, which he is not liable to pay rent except for any period to which regulation 8(1)(d) (waiver of rent by landlord in return for work done) applies.
2 In the case of the beginning or ending of a claimant’s rent-free period, his eligible rent for the benefit week in which the rent free period begins and ends shall be calculated on a daily basis as if those benefit weeks were weeks to which regulation 80(3) applies.
3 For the purpose of determining the weekly applicable amount and income of a claimant to whom this regulation applies, the weekly amount of any non-dependant deductions and the minimum amount payable in his case—
(a) in a case to which regulation 80(2)(a) applies, the amounts determined in his case in accordance with Parts 5 to 8 (applicable amounts, income and capital, students and amount of benefit) shall be multiplied by 52 or 53, whichever is appropriate, and divided by the number equal to the number of weeks in that 52 or 53 week period in respect of which he is liable to pay rent;
(b) subject to paragraph (4), in a case to which regulation 80(2)(b) or (c) applies, the amounts determined in his case in accordance with Parts 5 to 8 shall be multiplied by 365 or 366, whichever is appropriate and divided by the number of days in that 365 or 366 day period in respect of which he is liable to pay rent.
4 In a case to which paragraph (3)(b) applies, where either regulation 80(4) or (5) also applies or it is the beginning or end of a rent-free period, the weekly amounts referred to in paragraph (3) shall first be calculated in accordance with sub-paragraph (b) of that paragraph and then determined on a daily basis in the same manner as the claimant’s eligible rent.”

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Relevant amending instruments are S.I. 2005/2502 (as amended by S.I. 2006/217) and 2006/2378.
The relevant amending instrument is S.I. 2005/2502 (as amended by S.I. 2006/217).