Planning Guides
Costs & Timelines
2025-06-04 | Alejandro Trinco
Hidden Council Costs: Pre-App, CIL & More for a Rear Extension
A 45sqm rear extension sounds simple—until you meet pre-application fees, the Planning Portal charge, condition discharge costs and the sometimes-scary Community Infrastructure Levy (CIL). We priced the same scheme across Islington, Waltham Forest and Wyre Forest to show how council-side costs stack up—and how a single CIL exemption form can save £10k–£50k+ if you go bigger.
What we’re costing (England) – a 45sqm single-storey rear extension
A like-for-like householder application (not PD), 45sqm GIA on a typical dwelling.
We include: pre-application advice, planning application fee, Planning Portal service charge, one conditions discharge, and one non-material amendment (NMA).
We also show a “what-if”: the CIL bill if you built 120sqm without claiming the residential extension exemption.
Householder application fee (England): £528 (from 1 Apr 2025). ecab.planningportal.co.uk
Portal service charge: £70.83+VAT = £85 when you apply online. planningportal.co.uk
CIL on a 45sqm extension is £0 if you’re under 100sqm or you validly claim the residential extension exemption before starting works. buckinghamshire.gov.ukgov.uk
Pre-app and post-decision fees vary a lot by council (see table and sources).
Case study costs by council (45sqm, householder planning route)
Council | Pre-app (written) | App fee | Portal fee | 1× condition discharge | 1× NMA | CIL @45sqm | Total |
Islington (GLA Band 1) | £480 | £528 | £85 | £86 | £44 | £0 | £1,223 |
Waltham Forest (GLA Band 2) | £319 | £528 | £85 | £86 | £44 | £0 | £1,062 |
Wyre Forest (no CIL adopted) | £70 | £528 | £85 | £86 | £44 | £0 | £813 |
Sources: Islington pre-app fees (updated 2 Jan 2025): £400+VAT written; £584+VAT with site visit. islington.gov.uk Waltham Forest householder advice service £319 inc VAT (Mar 5 2025). walthamforest.gov.uk Wyre pre-app £70 written / £120 meeting (Apr 2024). Wyre Council Householder fee £528; discharge £86; NMA £44 (from 1 Apr 2025). ecab.planningportal.co.uk Portal service charge £70.83+VAT. planningportal.co.uk Wyre Forest has no CIL (charging schedule not adopted). rdcpublic.blob.core.windows.net
Why CIL suddenly matters if you go bigger (or miss the forms)
For extensions under 100sqm, CIL is automatically exempt. For 100sqm+, you can still get residential extension exemption—but only if you apply and are granted before starting work (CIL Form 9). Miss it, and you’re fully liable. buckinghamshire.gov.ukecab.planningportal.co.uk+1
“What-if” CIL bill (120sqm extension, no exemption claimed)
Council | Local CIL 2025 | Mayoral CIL (MCIL2) 2025 | Approx total rate | CIL on 120sqm |
Islington | £0–£400/sqm (by zone/type) | £94.79/sqm (Band 1) | £94.79–£494.79/sqm | £11,375 – £59,374 |
Waltham Forest (Zone A) | £106.34/sqm | £71.09/sqm (Band 2) | £177.43/sqm | £21,292 |
Wandsworth (Nine Elms Area A) | £1,008.18/sqm (local) | £94.79/sqm (Band 1) | ~£1,102.97/sqm | ~£132,356 |
Sources & notes: Islington states charges vary £0–£400/sqm; MCIL2 2025 Bands list Islington in Band 1. islington.gov.ukLondon City Hall+1 Waltham Forest Annual CIL Rate Summary 2025 (residential Zone A £106.34/sqm) + MCIL2 Band 2 £71.09/sqm. walthamforest.gov.ukLondon City Hall Wandsworth Annual CIL Rate Summary 2025 shows Nine Elms £1,008.18/sqm local CIL for residential (add MCIL2 Band 1 for total). (Illustrative high-rate example; not part of the 45sqm table.) Wandsworth Borough Council
Lesser-known tactics that cut risk (and cost)
Use PD + Lawful Development Certificate (Proposed) where possible. An LDC (Proposed) is half the full fee (so £264 for a householder enlargement) and can avoid pre-app and a full planning risk. ecab.planningportal.co.uk
Always submit CIL forms with your application: Form 1 (Additional Information) and, if 100sqm+, Form 9 (Residential Extension Exemption) before starting. Forgetting can trigger a five-figure bill. ecab.planningportal.co.uk+1
London only: remember Mayoral CIL (MCIL2) is on top of local CIL where development is liable. London City Hall
Post-decision admin: budget for at least one condition discharge (£86); avoidable NMAs (£44) still add up—so nail drawings first. ecab.planningportal.co.uk
England vs Wales (quick note)
Typical householder fee is £528 in England vs £190 in Wales (different regimes). If you’re near the border, don’t assume fees are the same. planningportal.co.uk
Disclaimer & jurisdiction: This guide covers England rules and fees as at 31 August 2025. Always check your council’s latest fee pages and Annual CIL Rate Summary for the permission year relevant to you. walthamforest.gov.uk
Hidden Council Costs: Pre-App, CIL & More for a Rear Extension
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