Count other families' children and add the foster and overnight-care bedrooms in the LHA size criteria

[MaxGhenis]

Fixes #2011

Stacked on #2010 (base lha-bedroom-young-people), which is stacked on #2006 and #1896. Retarget to main once they merge.

Problem

The LHA size criteria had three gaps:

1. Other families' children. bedrooms_for_children counted only the claimant's own benefit unit, so a grandchild living with their parent in the renter's home never had a room. Under Housing Benefit, neither did a boarder's or lodger's child.
2. Foster children. They had a bedroom of their own, and the foster parent had no additional bedroom. lha_renter_has_non_dependant also counted a foster child under 16 as a non-dependant, which took a single foster parent under 35 out of the shared accommodation rate for the wrong reason.
3. Overnight care. There was no additional bedroom for non-resident overnight carers.

The law, and how DWP applies it

All provisions were read on legislation.gov.uk on 2026-10-01. An independent legal research memo checked each reading against DWP guidance and case law; its verdicts are below.

Universal Credit (UC Regs 2013 Sch 4):

• The extended benefit unit is the renter, the children and qualifying young persons they are responsible for, and "any person who is a non-dependant" (para 9(1)).
• A non-dependant is anyone who normally lives with the renter, with seven exceptions in para 9(2). Three matter here:
  • (c): the renter's foster child;
  • (d): a person liable on a commercial basis, such as a lodger or joint tenant;
  • (g): "a child or qualifying young person for whom no-one in the renter's extended benefit unit is responsible".
• A non-dependant is responsible for their own child (reg 4(2)), so that child is a non-dependant and counts under para 10(1)(d)-(f).
  • The Explanatory Memorandum to SI 2013/2828, which inserted (g), says the same (para 7.22).
  • DWP's staff guidance Housing Costs Contributions – non-dependants (V13.0, deposited in Parliament as DEP2023-0791) says: "children can be expected to share rooms together, such as children of the main claimant or claimants with those of non-dependants".
• A lodger's or joint tenant's child is outside the extended benefit unit: the parent is excluded by (d), so (g) excludes the child. EM 2013/2828 para 7.6 says the same of joint tenants' children.
• No one is responsible for a child looked after by a local authority (reg 4(6)(a)), such as a foster child. The exception is a child placed for adoption (reg 4A(1)(c), from 1 April 2024).
• Para 12 gives one additional bedroom for each condition met (12(9)):
  • Overnight care condition. The renter, a member of the extended benefit unit, or a foster child receives a listed benefit and has carers who do not live in the home, engaged to stay overnight regularly ((A1), (3)).
  • Foster parent condition. The renter is a foster parent, or an adopter with a child placed. This continues for 12 months between placements ((4)-(5)).
  • ADM F3138 example 1 confirms that two people needing overnight care still give one bedroom; example 2 confirms that the overnight-care and foster rooms are cumulative.
• A foster parent is excepted from the shared accommodation rate (para 29(9A)).
• The para 29(5) disability exception includes armed forces independence payment, because reg 2 defines "attendance allowance" to include it.

Housing Benefit (HB Regs 2006 and HB (SPC) Regs 2006, reg 13D):

• One bedroom for each category of "occupier": everyone the authority is satisfied occupies the dwelling as their home, except a joint tenant outside the claimant's household (13D(12)).
  • LHA Guidance Manual paras 2.030-2.031 list non-dependants, boarders and sub-tenants as occupiers. HB/CTB circular A4/2012 para 44 says the same of lodgers.
  • Their children are occupiers too. The Upper Tribunal in Hockley (quoted at [2019] AACR 27, para 9) put the method as "identify the individuals who occupy the dwelling as their home and then to place them into the categories".
• A joint tenant's household is not counted: "the calculation is based on each tenant's individual household size" (circular A21/2013 para 25; LHA Guidance Manual para 2.093; A3/2017 example 10).
• A child or young person placed with the claimant as a foster child or for adoption is not a member of the household "nor ... occupying the claimant's dwelling" (reg 21(3)).
• A "qualifying parent or carer" (reg 2(1)) has one additional bedroom (13D(3A)(b)). So does a household where a "person who requires overnight care" lives (13D(3A)(a)). Both together give two (13D(3B)). Neither such claimant is a "young individual" for the shared accommodation rate.
• HB's children's categories are assigned "first category only which applies". DWP applies them combinatorially: "A child is required to share where there is no combination of sharing consistent with the size criteria which allows them their own bedroom" (A21/2013 para 13). So the fewest-rooms allocation serves both schemes.

Change

	Universal Credit (LHA_allowed_bedrooms)	Housing Benefit (housing_benefit_LHA_allowed_bedrooms)
Children counted for the household head	own children + non-dependants' children, pooled	own + non-dependants', boarders' and lodgers' children, pooled
Joint tenant's (sharer's) children	not counted (para 9(2)(d), (g))	not counted (13D(12); A21/2013 para 25)
Foster child	no room; carer +1 (lha_renter_meets_foster_parent_condition)	not an occupier; carer +1 (is_housing_benefit_qualifying_parent_or_carer)
Child placed for adoption	counts as the adopter's child, and adopter +1	not an occupier; adopter +1
Overnight care	+1 if the renter, anyone in the extended benefit unit or a foster child meets the condition	+1 if the claimant, partner, another occupier or a placed child requires overnight care
Shared accommodation rate	foster parent excepted (29(9A)); AFIP added to 29(5)	qualifying parent or carer and a person who requires overnight care are not young individuals
Occupier couple from another family (non-dependant, boarder or lodger)	one bedroom each (para 10(1)(c); ADM F3112 note 1), unchanged	one bedroom between them (13D(3)(a), "a couple"; LHA Guidance Manual para 2.012). Before, each member had one

New variables:

• Additional bedrooms: LHA_additional_bedrooms, housing_benefit_LHA_additional_bedrooms.
• Conditions: meets_lha_overnight_care_condition, lha_renter_meets_foster_parent_condition, is_housing_benefit_qualifying_parent_or_carer.
• is_child_or_young_person_placed_with_family: the reg 21(3) placement test. is_child_or_young_person_for_legacy_benefits now uses it, so children placed for adoption also leave the legacy household (IS reg 16(4), JSA reg 78(4), ESA reg 156(5), HB reg 21(3)).
• tax_free_childcare_qualifying_child excludes a child placed for adoption (Childcare Payments (Eligibility) Regs 2015 reg 4(2)(d)). Each scheme treats an adoption placement differently:
  • Universal Credit and Pension Credit treat the adopter as responsible (UC reg 4A(1)(c); SPC Sch IIA para 4(3)(c)), which the model already did.
  • Under HB, IS, JSA, ESA and three CTR schemes, the child is not in the household. The CTR schemes are English pensioner (SI 2012/2885 reg 8(2)(b)-(c)), Welsh (SI 2013/3029 reg 8(2)(b)-(c)) and Scottish pension-age (SSI 2012/319 reg 11(2)(b)-(c)).
  • Scottish working-age CTR (SSI 2021/249 reg 7(8)) excludes only foster placements, so there the child should count. The model's shared legacy household test leaves them out. This is a known gap.
  • youngest_child_age_for_legacy_benefits, which drives Income Support lone-parent eligibility, now also leaves out a child placed with the family (IS reg 16(4)).
  • Under CTC, the child is excluded only while the local authority pays for their keep (reg 3, rule 4 case B). The model can't observe that, so CTC is unchanged.

New inputs, all default false:

• is_placed_for_adoption;
• is_approved_foster_parent_without_placement;
• has_non_resident_overnight_carer.

A foster child is a household member with the existing is_looked_after_by_local_authority, now documented for that use.

New parameters:

• gov.dwp.LHA.overnight_care_benefits lists the qualifying benefits: attendance allowance, AFIP, DLA care at the middle or highest rate, and the PIP daily living component. The law also lists the Scottish devolved equivalents (child disability payment, adult disability payment, Scottish adult DLA, pension age disability payment). The model has no variables for those, so they count only where the data records them as the DWP benefits. The same is true of the para 29(5) list, a gap that predates this PR.
• household.demographic.looked_after_child_age_limit (18).
• gov.dwp.LHA.overnight_care_beyond_claimant: false before 1 April 2017, true from then (SI 2017/213). Before that date only the renter, or the HB claimant and partner, could meet the overnight care condition.

New variables:

• is_looked_after_child: is_looked_after_by_local_authority and under 18. Only a child, a person under 18, can be looked after (Children Act 1989 ss.22(1) and 105(1)), so the flag has no effect at 18 or over.
  • It replaces the raw flag in the UC, CTC and Pension Credit child tests and in is_child_or_young_person_placed_with_family.
  • Without it, a flagged 18- or 19-year-old qualifying young person dropped out of UC while still giving an HB carer room. A single renter under 35 then got the shared rate.
• is_lha_foster_child: a looked-after child placed with the renter (see judgment call 5).

Income Support: income_support_eligible now includes Sch 1B paras 2 and 2A: "a single claimant or a lone parent with whom a child is placed" by a local authority, or placed for adoption by an adoption agency. Without them, leaving placed children out of the youngest-child test would have taken eligibility from a lone parent whose only child under 5 is a foster or adoptive placement.

bedrooms_for_children is split into an arithmetic rooms_for_children and a wrapper that takes masks for the family's own children and other families' children.

Judgment calls for review

1. UC adopters get two rooms.
   • The child counts because reg 4A(1)(c) makes the adopter responsible, and the adopter also gets the para 12(4)(b) room.
   • The current text gives both, and ADM F3133 still lists adopters. No guidance addresses the combination; EM to SI 2024/341 para 7.5 is about the child element.
   • Before 1 April 2024 the position is unclear. EM 2024/341 implies DWP treated these children as looked after. But the old reg 4A(1)(b) already excluded placements with "a person who has parental responsibility", and prospective adopters have parental responsibility (Adoption and Children Act 2002 s.25(3)). The model applies the current rule in every year.
   • The reg 89(3)(a) definition of adopter, which excludes a foster parent or close relative of the child, is not checked.
2. HB: a child placed with someone other than the claimant is not an occupier. This covers, for example, a non-dependant's foster child or adoption placement.
   • Reg 21(3) names only placements "with the claimant or his partner", so on the text such a child is an occupier with a room.
   • The model follows DWP's general treatment instead, which also matches UC (para 9(2)(g)). The LHA Guidance Manual says foster children "do not occupy the dwelling" (para 2.033), though that passage is about the claimant's own foster children. A21/2013 para 22 records DWP treating a joint tenant as under-occupying when the spare room held the other tenant's foster child.
   • The independent legal memo rated this "supported by the text, with a contrary DWP indication". For a renter of 60 with a non-dependant daughter fostering a child of 6, the model gives 2 bedrooms; the literal text gives 3.
3. HB reg 21(3)(a) and s.22C(2).
   • Since SI 2017/901, reg 21(3)(a) refers to a placement "under section 22C(2) of the Children Act 1989". That is placement with a parent; foster placements are s.22C(5)-(6), and the earlier text cited s.23(2)(a).
   • The model treats foster placements as within reg 21(3), as the "qualifying parent or carer" definition presupposes. The English pensioner CTR rule says so expressly ("section 22C", SI 2012/2885 reg 8(2)(a)), as does the Welsh one ("section 22C or 23(2)(a)", SI 2013/3029 reg 8(2)(a)).
   • On the current text, a looked-after child placed back with a parent is also outside the HB household. The model can't represent that alongside UC's reg 4A(1)(b), which keeps such a child in the household. Listed under known gaps.
4. Not observed.
   • HB's qualifying parent or carer, and the HB overnight-care carer, need a spare bedroom in the dwelling (A3/2017 example 10). The model has no count of the dwelling's bedrooms (num_bedrooms is unused and not in the data), so it assumes there is one.
   • HB's alternative overnight-care route, where the authority accepts evidence instead of a listed benefit, is not modelled either.
5. UC "child" means under 18 for foster children.
   • Reg 2 makes a foster parent "a person with whom a child is placed" under the care planning regulations, which place children under 18. Para 9(3) defines a foster child as "a child" in relation to whom the renter is a foster parent, and para 12(A1)(c) refers to "a child".
   • WRA 2012 s.40 defines a child as under 16, unless the contrary intention appears (Interpretation Act 1978 s.11). Reg 91(2)(b)-(d) speaks of foster parents of qualifying young persons.
   • The model reads "child" as under 18 in all three places (is_lha_foster_child). A looked-after 16- or 17-year-old placed with the renter is therefore a foster child: they have no room of their own, the renter has the foster room, and their overnight care counts.
   • Reading "child" as under 16 throughout gives the same total for a looked-after 17-year-old not in education (2). It differs for a looked-after qualifying young person (1 instead of 2), which reverses Give benefit-unit members aged 16 or over a bedroom in the LHA size criteria #2010's expected value for that case.
   • The review put the under-18 reading at about 65-75% likely to be what a decision maker applies. No guidance or case law addresses it.
   • The shared lha_renter_has_non_dependant still counts a looked-after 17-year-old not in education as a non-dependant. A 16-year-old is caught by its separate age-16 rule. That is right for HB and, on this reading, wrong for UC. Apply each scheme's own non-dependant test to the LHA shared accommodation rate #2030 splits that variable into UC and HB versions and excludes is_lha_foster_child from the UC one.
6. HB overnight care for other occupiers.
   • 13D(3A)(a)(iii) reads "a person ... who occupies the claimant's dwelling as their home", without the defined term "occupiers". On the text, it could reach a joint tenant outside the claimant's household.
   • The model applies 13D(12)'s exclusion of such a joint tenant, and of a child placed with another family. In the private sector, joint tenants' size criteria rest on each tenant's own household (A21/2013 para 25). A3/2017 also frames the 2017 extension as a room for carers of a disabled child or non-dependant.
7. Dates.
   • The overnight-care extension is gated at 1 April 2017. The model reads gov parameters at 30 April of each year (its fiscal-year convention), so the extension applies from model year 2017, which is 2017-18.
   • UC para 29(9A), the foster parent exception, has been in law since 28 November 2018 (SI 2018/1129). The model applies it in every year, because EM 2018/1129 para 7.12 describes it as DWP's existing policy before then.

Invariants

The Hypothesis properties are in test_lha_bedroom_young_people_properties.py: 5 properties, 25 derandomized examples each.

• Generators. They make up to 4 households, each with a head family and up to 2 others (sharers, boarders, lodgers, non-dependants). A family has 1-2 adults and up to 4 children; children are own, fostered or placed for adoption. Overnight care and between-placements carers also appear.
• The added person aged 16 to 19 is biased towards being looked after, in education and not on benefits in their own right, and sometimes has overnight care.
• Status comes from inputs. The tests work out the added person's status from the inputs alone, using their own predicates: UC reg 5 qualifying young person, the Child Benefit qualifying young person for HB reg 19, and looked after under 18 for a foster child. They do not read it from the model.

1. Monotonicity. Adding a person aged 16 to 19 never lowers any family's UC or HB bedrooms. This holds with the claimant and partner supplied or inferred.
2. Exact effect of a person aged 16 to 19. This extends Give benefit-unit members aged 16 or over a bedroom in the LHA size criteria #2010's property:
   • A qualifying young person no one is responsible for, or a foster child under 18, has no UC room of their own. A young person placed under reg 21(3) has no HB room.
   • The family they are placed with gains the foster or carer room if it did not have it already.
   • Their effect on the household head's family follows the same rules.
3. Children. Adding a child under 16 who is neither fostered nor placed for adoption raises each family's bedrooms by 0 or 1, under each scheme.
4. Foster children. Adding a foster child gives the carer family exactly one more bedroom if it did not already meet the foster condition, and none otherwise. No other family's bedrooms change under either scheme.
5. Reference count. Each family's bedrooms and additional bedrooms equal a count made by the test.
   • Children's rooms are the fewest rooms holding the pooled children two to a room, found by brute force. This also checks the greedy arithmetic in rooms_for_children against the optimum. The review separately checked it exhaustively for every composition of up to 24 children.
   • The count applies the same legal readings as the model, including the judgment calls above. It checks that the code implements those readings, not that the readings are right. The YAML cases carry the hand-derived legal expectations.

Mutation check. Each mutation below was applied to a scratch copy of the branch, and each makes at least one property fail:

• no pooling of non-dependants' children (UC);
• foster children given their own UC rooms;
• one overnight-care room per person instead of one in total;
• HB counting a joint tenant's children;
• no mixed-sex sharing for children under 10;
• adopters without the UC para 12(4)(b) room.

The round-1 review found four mutants that survived the earlier tests:

• "placed" without the Child Benefit young-person test;
• a non-dependant's foster child's overnight care counting under UC;
• reverting (A1)(c) for a looked-after qualifying young person;
• a looked-after claimant giving the foster room.

The round-2 review ran real mutant copies against the YAML file. The first three each fail at least one case. The fourth is now pinned by a 17-year-old looked-after claimant case. The property generator supplies claimant roles, so the properties cannot reach that fourth mutant.

Tests

• New LHA_other_families_children_and_additional_bedrooms.yaml: 35 cases. Expectations are hand-derived from the law and guidance cited in each case's comments.
  • Run against this PR's base (49866c2), 16 cases run once the new inputs and outputs are stripped. 7 fail, as expected:
    • non-dependants' children (2 cases);
    • a non-dependant couple under HB;
    • a lodger's child under HB;
    • foster children (2 cases);
    • AFIP.
  • The other 9 pass on the base. Some are guards: same-sex pooling, a joint tenant's child, a non-dependant's foster child, an inconsistent couple flag, and a disability benefit without a carer. In the rest, the old rules happen to give the same total, as with the fostering couple and the boarder couple with a child.
  • The remaining cases use the new inputs or variables, or assert only new outputs.
• LHA_young_person_bedroom.yaml: the looked-after qualifying young person case expects the carer's foster room: UC 1 → 2 bedrooms, category B → C. HB stays at 2, now as the carer's room rather than the young person's. The comment states the under-18 reading (judgment call 5).
• tax_free_childcare_qualifying_child.yaml: a child placed for adoption is not a qualifying child.
• income_support.yaml: four cases. A single foster carer, and a lone parent with an older own child and a young foster child, are in IS Sch 1B para 2. The same two households with an adoption placement instead are in para 2A.
• At e5c36dc: policyengine-core test policyengine_uk/tests/policy -c policyengine_uk: 1,547 passed.
• At 500424e (the later commit changes only Income Support and YAML):
  • policyengine-core test policyengine_uk/tests/policy -c policyengine_uk: 1,544 passed.
  • Hypothesis (this PR's file): 5 properties pass.
  • test_child_and_adult_definitions_properties.py: 9 passed. Its reference now applies the under-18 limit to the looked-after flag.
  • test_means_test_income_properties.py and test_rent_of_sharers_boarders_and_lodgers_properties.py: 7 passed.
• Full pytest at bee86d9 (pytest policyengine_uk/tests --ignore=policyengine_uk/tests/microsimulation, property file run separately): 2,052 passed, 19 skipped. That includes test_oldest_person_is_head_and_gets_rent, which Give benefit-unit members aged 16 or over a bedroom in the LHA size criteria #2010 reported failing on Give sharers, boarders and lodgers their own rent, tenure and LHA category #2006's earlier head. It was not re-run in full at later heads, to keep host load down; the test files covering what the later commits change were run as above.
• ruff format and ruff check: clean.

Impact (real microsimulation)

Data: the enhanced FRS 2024-25 as released (policyengine-uk-data 1.57.4, enhanced_frs_2024_25.h5, sha256 03fe15e4…), year 2026. Base is #2010's head, 49866c2; the branch is 500424e (084664c and 9311e4e give identical aggregates). The head, e5c36dc, changes only Income Support eligibility for foster and adoption placements, which are not in the data, and YAML tests. Both runs use the same dataset.

A survey household is identified by its rent and its members' ages, which every enhanced-FRS record shares with its FRS 2024-25 source household. Cells built from fewer than 10 survey households are suppressed. Sub-cells are suppressed together when any one of them is below the threshold, so no hidden cell can be recovered by subtraction.

• Children under 16 in a non-dependant's family: 135k (64 survey households).
• Boarder or lodger families, or sharers' families, with children: 0. The released data has no boarder or lodger rent yet (policyengine-uk-data#506 and Add Energy Bills Rebate #512 are drafts).
• UC bedroom counts: rise for 109k benefit units (62 survey households). None falls.
• HB bedroom counts:
  • fall for 430k benefit units (66 survey households), because an occupier couple now counts once;
  • rise for 66k (47 survey households), because of non-dependants' children.
• Private renters, the only group whose LHA depends on the bedroom count:
  • UC changes affect fewer than 10 survey households, so UC categories, the housing costs element and UC paid are suppressed.
  • HB categories change for 22k benefit units (12 survey households); each transition is suppressed.
  • The HB eligible rent under the LHA (LHA_cap, computed for every private renter whether or not they claim) rises by £14.7m net.
  • HB paid is unchanged: no private-renting HB recipient is affected.
• Poverty (BHC and AHC): no change.
• Foster, adoption and overnight-care inputs: default false and not in the data, so those changes have no microsimulation effect.
• AFIP: the data has no recipients.
• Shared accommodation: UC specified-renter and HB young-individual flags are unchanged.

Known gaps (not changed here)

• Disabled child and disabled couple rooms (UC para 12(1)(c)-(d), (6), (6A), (8); HB 13D(3)(za), (ba)) are not modelled. They are being done on branch lha-disabled-cannot-share-rooms.
• Temporary absence (UC para 11; HB reg 7) and the armed forces rule are not modelled.
• Shared non-dependants for joint tenants. HB counts a non-dependant shared by joint tenants in each joint tenant's size criteria (LHA Guidance Manual para 2.110). The model gives non-dependants only to the household head's family; branch hb-joint-tenant-shared-non-dependant (Count a non-dependant shared by joint tenants in each tenant's Housing Benefit size criteria #2029) changes that.
• Head family. Other families are attributed only to the household head's family. With no head input, the eldest adult becomes the "renter", even if a lodger.
• Joint tenant in the claimant's household. A joint tenant who is a member of the claimant's household is treated as a separate sharer (LHA Guidance Manual para 2.100, the Lee example).
• HB evidence route for overnight care, and the spare-bedroom conditions (judgment call 4).
• Scottish working-age CTR should count a child placed for adoption in the household (SSI 2021/249 reg 7(8)). The shared legacy household test leaves them out.
• A looked-after child placed back with a parent is outside the HB household on the current text of reg 21(3)(a). The model keeps them in, as UC does.
• HB "eligible children". HB reg 19(2)(c) excludes from "young person" anyone covered by Children (Leaving Care) Act 2000 s.6. That covers an eligible child: a looked-after 16- or 17-year-old who has been looked after for 13 weeks since age 14. Such a person is an occupier with a room, and gives no carer room. The model has no input for it and treats every looked-after qualifying young person as placed. Totals usually match, because an occupier room replaces the carer room.
• Scottish devolved disability benefits are not modelled separately (see New parameters; Include the Scottish devolved disability benefits in the LHA size-criteria benefit lists #2041).

Documentation

The variables' documentation fields describe the rules. No docs notebook covers the size criteria.

axiom: uk/regulations/uksi/2013/376/schedule/4/paragraph/10 (UC Sch 4 para 10(1)(d)-(f), (3)(b)) encoded-correct, companion cases in TheAxiomFoundation/rulespec-uk#412 | UC Sch 4 para 9(2)(c), (g) (non-dependants' children, foster children): TheAxiomFoundation/rulespec-uk#406 queued (addendum: TheAxiomFoundation/rulespec-uk#406 (comment)) | UC Sch 4 paras 12 and 29(5), (9A): TheAxiomFoundation/rulespec-uk#411 queued | HB Regs 2006 / HB (SPC) Regs 2006 regs 2(1), 13D(3)(c)-(e), (3A)-(3B), (12), 21(3): TheAxiomFoundation/rulespec-uk#406 and #357 queued (addenda: TheAxiomFoundation/rulespec-uk#406 (comment), TheAxiomFoundation/rulespec-uk#357 (comment))

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