Data Sources of Record

Every numeric claim on this site is tied to one of the primary sources below. Verified 2026-09-17. Re-verified quarterly; see the changelog for the audit log.

BCIS (RICS Building Cost Information Service) £/m² study data

Owner: RICS · Vintage: Subscription data. Regional £/sqm figures on this site are BCIS figures as reprinted in named council viability studies (BCIS data dated Nov 2024 to Jul 2026), each linked where it is used

National Planning Policy Framework (August 2026)

Owner: MHCLG · Vintage: Published 17 August 2026 (first comprehensive rewrite since 2012), in force; supersedes the Dec 2024 framework

National Planning Policy Framework (August 2026)· Published 17 August 2026 (first comprehensive rewrite since 2012), in force; supersedes the Dec 2024 framework

Planning Practice Guidance: Viability

Owner: MHCLG · Vintage: Last updated 16 December 2025; suggests 15-20% of GDV developer return (paragraph 019)

Planning Practice Guidance: Viability· Last updated 16 December 2025; suggests 15-20% of GDV developer return (paragraph 019)

RICS Valuation Global Standards (Red Book)

Owner: RICS · Vintage: Effective 31 Jan 2025

RICS Valuation Global Standards (Red Book)· Effective 31 Jan 2025

HM Land Registry Price Paid Data

Owner: HM Land Registry · Vintage: Q1 2026 release

HM Land Registry Price Paid Data· Q1 2026 release

Stamp Duty Land Tax (SDLT)

Owner: HMRC · Vintage: Current rules post-31 Mar 2025

Stamp Duty Land Tax (SDLT)· Current rules post-31 Mar 2025

Land and Buildings Transaction Tax (LBTT)

Owner: Revenue Scotland · Vintage: 2026/27 bands

Land and Buildings Transaction Tax (LBTT)· 2026/27 bands

Land Transaction Tax (LTT) Wales

Owner: Welsh Revenue Authority · Vintage: 2026/27 bands

Land Transaction Tax (LTT) Wales· 2026/27 bands

Community Infrastructure Levy

Owner: DLUHC (MHCLG) · Vintage: Current statutory regime

Community Infrastructure Levy· Current statutory regime

Biodiversity Net Gain guidance

Owner: Defra · Vintage: Statutory since 12 Feb 2024 (major sites) and 2 Apr 2024 (small sites); new 0.2ha small-site exemption and removal of self-build exemption from 6 Aug 2026

Biodiversity Net Gain guidance· Statutory since 12 Feb 2024 (major sites) and 2 Apr 2024 (small sites); new 0.2ha small-site exemption and removal of self-build exemption from 6 Aug 2026

Permitted Development Rights

Owner: DLUHC (MHCLG) · Vintage: Class MA and Q current

Permitted Development Rights· Class MA and Q current

Technical Housing Standards (NDSS)

Owner: DLUHC (MHCLG) · Vintage: Applies to PDR conversions from 6 Apr 2023

Technical Housing Standards (NDSS)· Applies to PDR conversions from 6 Apr 2023

HMRC VAT431NB DIY housebuilders reclaim

Owner: HMRC · Vintage: Digital portal active

HMRC VAT431NB DIY housebuilders reclaim· Digital portal active

UK Finance data and research

Owner: UK Finance · Vintage: Q1 2026

UK Finance data and research· Q1 2026

Bank of England statistics

Owner: Bank of England · Vintage: Current bank rate 3.75 percent (held 17 Sep 2026, 6-3 vote)

Bank of England statistics· Current bank rate 3.75 percent (held 17 Sep 2026, 6-3 vote)

ONS construction output inflation

Owner: ONS · Vintage: Latest monthly

ONS construction output inflation· Latest monthly

UK House Price Index

Owner: HM Land Registry / ONS · Vintage: April 2026 release

UK House Price Index· April 2026 release

Mayoral CIL2 Annual CIL Rate Summary 2026

Owner: Greater London Authority · Vintage: 2026-indexed rates (Ip=400/Ic=330): Band 1 £96.97, Band 2 £72.73, Band 3 £30.30 per sqm

Mayoral CIL2 Annual CIL Rate Summary 2026· 2026-indexed rates (Ip=400/Ic=330): Band 1 £96.97, Band 2 £72.73, Band 3 £30.30 per sqm

Camden Annual CIL Rate Summary 2025

Owner: London Borough of Camden · Vintage: Rates for permissions granted in 2025 (issued 1 Nov 2024)

Camden Annual CIL Rate Summary 2025· Rates for permissions granted in 2025 (issued 1 Nov 2024)

Hackney CIL charging schedule and zone map

Owner: London Borough of Hackney · Vintage: Charging schedule in effect from 1 April 2015 (base rates)

Hackney CIL charging schedule and zone map· Charging schedule in effect from 1 April 2015 (base rates)

Wandsworth Annual CIL Rate Summary 2026

Owner: London Borough of Wandsworth · Vintage: Rates for 2026 (index 400 / 223)

Wandsworth Annual CIL Rate Summary 2026· Rates for 2026 (index 400 / 223)

Lewisham Annual CIL Rate Summary 2026

Owner: London Borough of Lewisham · Vintage: Rates for 1 Jan to 31 Dec 2026 (index 400 / 259)

Lewisham Annual CIL Rate Summary 2026· Rates for 1 Jan to 31 Dec 2026 (index 400 / 259)

Southwark Annual CIL Rate Summary 2026 (Part 2)

Owner: London Borough of Southwark · Vintage: Third charging schedule, permissions from 29 Sep 2026

Southwark Annual CIL Rate Summary 2026 (Part 2)· Third charging schedule, permissions from 29 Sep 2026

Tower Hamlets Annual CIL Rate Summary 2026

Owner: London Borough of Tower Hamlets · Vintage: CIL2 rates for 2026 (index 400 / 334)

Tower Hamlets Annual CIL Rate Summary 2026· CIL2 rates for 2026 (index 400 / 334)

Tower Hamlets CIL Charging Schedule 2020 (Appendix 1 charging-zone maps)

Owner: London Borough of Tower Hamlets · Vintage: CIL2 charging schedule in effect from 17 January 2020; residential zone map dated 10 Oct 2019

Tower Hamlets CIL Charging Schedule 2020 (Appendix 1 charging-zone maps)· CIL2 charging schedule in effect from 17 January 2020; residential zone map dated 10 Oct 2019

BCIS (RICS Building Cost Information Service) £/m² study data· Subscription data. Regional £/sqm figures on this site are BCIS figures as reprinted in named council viability studies (BCIS data dated Nov 2024 to Jul 2026), each linked where it is usedAppraisal model reviewed by Oliver Wakefield-Smith (data integrity) with chartered-surveyor (MRICS) and CTA tax review. No affiliate links.