Under the current household-relief procedure, the surcharge is generally 20% of the notional charge or £2,500, whichever is lower. Failing to obtain an exemption before starting is a separate issue and can expose the full levy, not merely that surcharge. [1][2]
What the notice actually does
Form 6 tells the collecting authority when chargeable development will commence. It must be received before the start date. Sending building-control information, booking an inspection or telling the planning case officer about the programme is not the same as completing this CIL requirement. [1][3]
Do not leave the notice until the morning construction is due to begin. Agree the actual start with the contractor, use the correct CIL reference and retain evidence that the collecting authority received it. The official form makes the timing a prerequisite, rather than a notification to send whenever convenient. [1]
Calculate the penalty against the right figure
For an exempt self-build or annex under the post-2019 procedure, the surcharge is assessed against the amount that would have been chargeable without the exemption. It is not 20% of a zero balance after relief. [4][5]
As an illustration of the published formula, a notional liability of £10,000 gives 20% of £10,000, or £2,000. A £20,000 notional liability gives £4,000 before the cap, so the surcharge would be £2,500. These are worked examples, not typical CIL bills or an overall limit on every sum that could be due. [1]
For development where CIL is payable, failure to notify commencement can also remove the normal instalment arrangements. Richmond's guidance explains that the full charge can become payable on the commencement date determined by the authority. Separate late-payment consequences may then follow. [3]
Two distinctions that change the outcome
First, a missing commencement notice is not the same as a missing exemption grant. The household exemption must have been approved before work starts. The £2,500 surcharge cap does not turn an unapproved exemption into an approved one or cap the underlying CIL liability. [2][4]
Second, the current forms distinguish notices issued before 1 September 2019 from those issued on or after that date. For the older category, failure to submit the commencement notice can invalidate relief. Do not apply the newer surcharge-only distinction to an old notice without checking its history. [1]
A qualifying residential extension exemption under Form 9 is another exception: for a liability notice issued on or after 1 September 2019, that form says a commencement notice is not required. Annex and self-build exemptions do not share this exception. [6][5][4]
When work has already started
Contact the collecting authority promptly with the permission, liability and exemption notices, the actual work chronology and any evidence of earlier submission. Ask it to explain the legal basis and calculation of any demand or surcharge. Do not assume that sending a late form cancels a charge already triggered. [1][3]
MHCLG's 25 June 2026 letter proposes procedural reforms and discusses councils' existing discretion over enforcement and exceptional compensation. It is not a general waiver, refund scheme or retrospective exemption. Take case-specific professional advice where liability, enforcement or a disputed start date is involved. [2]