SPD inputs (10 supported LPAs)
Each supported LPA carries a hand-extracted rate set from the council's adopted Supplementary Planning Document. Birmingham (Affordable Housing SPD, TP30) [PPG Planning Obligations], Manchester (Core Strategy + Planning Obligations SPD), Leeds (CS7 + CIL), Bristol (Practice Note + CIL), Cornwall (Local Plan + AH SPD), RBKC (Planning Contributions SPD), Camden (Planning Obligations SPD + H4), Cambridge (Local Plan 2018 + Obligations SPD), Milton Keynes (Plan:MK + MK Tariff), plus a regional England mean fallback.
BCIS rebase
Per-pupil education rates, healthcare £/resident multipliers, and per-dwelling open-space costs are rebased to the BCIS All-in TPI snapshot for 2026 Q2 [BCIS All-in TPI]. The estimator does not roll forward general inflation between rebases; reset the rate set to the published BCIS index date.
CIL Regs reg 122 necessity test
Every head in the estimator was reviewed against reg 122[CIL Regs 2010 reg 122]. The three-limb test (necessary, directly related, fairly and reasonably related in scale and kind) is the gate that disqualifies a head before it is added to the figure. Healthcare contributions, for example, are conditional on a local ICB request with documented capital-shortfall evidence.
Monitoring fee constraint
The monitoring fee uses the £500 to £1,200 per-obligation range set by the CIL (Amendment) Regs 2019 reg 4 [CIL (Amendment) Regs 2019]. The estimator assumes six discrete obligations per deed and prices the fee accordingly; LPAs that itemise additional obligations (a phased AH delivery, for example) will price upward.
LURA 2023 and the 2026 Act treatment
The Infrastructure Levy pilots under LURA 2023 [Levelling-up and Regeneration Act 2023]are tracked but not applied to the live LPA rates because the pilot cohort has not yet hit the supported-LPA tier. The 29 Apr 2026 amendments in the English Devolution and Community Empowerment Act are treated as live regulation and reflected in the changelog; the rate layer is unchanged because the amendments do not alter the reg 122 test or the per-head rates themselves.
Regional fallback
For an unsupported LPA, the estimator returns the mean of the 10 supported authorities. This is a deliberate floor, not a forecast. For a hand-verified figure the buyer should request the LPA's own Planning Obligations SPD and rebase against the local CIL charging schedule.
Limits
- The estimator is not a substitute for a chartered planner's drafting work.
- Per-pupil yield ratios use a mixed-tenure mean (0.21 primary / 0.14 secondary). Schemes weighted to family housing should adjust.
- Healthcare contributions are conditional and may be refused as ineligible under reg 122.
- BNG monetisation here is a placeholder; see /bng/units-calculator for the unit-cost model.