A regularisation certificate is the retrospective building regulations approval you apply for when work was carried out without the right consent – a loft conversion, an extension, a removed chimney breast, a knocked-through wall. In 2026 it matters more than ever: local authorities can now take enforcement action for up to ten years after unauthorised work, buyers’ surveyors flag missing certificates routinely, and lenders are increasingly reluctant to accept indemnity insurance alone. This guide explains what a regularisation certificate is, who can apply, what it costs in 2026, how long it takes and how a suitably qualified, accredited surveyor can get you through the process with the least disruption.
A regularisation certificate is a document issued by a local authority building control body confirming that building work carried out without building regulations approval has been inspected and, as far as can be ascertained, complies with the regulations that applied when it was built.
It is retrospective approval under regulation 18 of the Building Regulations 2010. Two things make it different from ordinary approval. First, it is only available from a local authority. Private registered building control approvers (formerly approved inspectors) cannot issue one, as GOV.UK confirms. Second, the council assesses the work against the regulations in force at the time the work was done, not today’s standards, which is why knowing roughly when the work happened matters.
Regulation 18 also states that the certificate is evidence, but not conclusive evidence, that the relevant requirements have been met, and that it implies nothing about planning permission. If your extension also needed planning consent, that is a separate question for the planning department.
Most people discover they need one at the worst possible moment: mid-sale. The typical triggers are:
Common work that ends up needing regularisation includes loft conversions, single and double-storey extensions, garage conversions, structural openings and steel beams, chimney breast removal, replacement windows (where not certified under a competent person scheme), new boilers and electrical rewiring, and drainage alterations. If a completed project has an inspection history and a completion certificate, you do not need regularisation; see our guide to the building regulations completion certificate for what that document should look like.
Under regulation 18, the owner of the building applies. The work must have been started on or after 11 November 1985, must have fallen within the scope of the regulations at the time, and must have had no building regulations application submitted for it. Work that pre-dates November 1985 cannot be regularised; in that situation a surveyor’s report on the condition of the work is usually the practical alternative.
There is no legal obligation to apply. Hertfordshire Building Control’s guidance puts it plainly: an owner is under no obligation to seek a regularisation certificate, but to sell a property it is often necessary, and it may be the only way to demonstrate compliance. Note also that if the building is a higher-risk building (broadly, residential buildings of at least 18 metres or seven storeys), building control functions sit with the Building Safety Regulator rather than the council, and different procedures apply.
Councils set their own charges under the Building (Local Authority Charges) Regulations 2010, but the structure is remarkably consistent across England and Wales. The regularisation charge is usually calculated as a percentage uplift of the equivalent building notice fee, most commonly 150%, and it is exempt from VAT. Because charges are reviewed annually, many councils published new schedules for 2026/27: Gateshead’s took effect on 1 April 2026, Preston increased fees by 10% from 1 April 2026, and BCP Council amended its scheme from 10 August 2026, citing inflation and the requirement to recover service costs.
| Application route | When it is used | Fee basis | VAT | Worked example (Gateshead, 1 new dwelling, from 1 April 2026) |
|---|---|---|---|---|
| Full plans | Before work starts; plans checked in advance | Plan charge + inspection charge | 20% | £498.24 + £934.20 |
| Building notice | Before work starts; smaller domestic jobs | Single charge | 20% | £1,432.44 |
| Regularisation | After work is complete without approval | 150% of ex-VAT building notice charge | Exempt | £1,790.55 |
Source: Gateshead Council Building Regulation Charges Guidance Notice 1, effective 1 April 2026. Your own council’s figures will differ; check its current scheme of charges before applying.
The council fee is rarely the whole cost. Expect to budget for some or all of the following:
There is no statutory decision period for regularisation, unlike full plans (five weeks, or two months by agreement). In practice the timeline is driven by three things: how quickly the council can inspect, how much opening up and remedial work is needed, and how promptly you respond to requests. Straightforward cases with good records can be certified within a few weeks; cases involving structural design, remedial fire protection or several site visits commonly take two to four months. If you are selling, start the process the moment the problem is identified and tell the buyer’s solicitor what you are doing.
Conveyancers frequently offer a lack-of-building-regulations indemnity policy as a quicker alternative. It has its place, but it is important to understand what it does and does not do.
| Feature | Regularisation certificate | Indemnity insurance |
|---|---|---|
| What it confirms | Work inspected and found to comply with the regulations in force at the time | Nothing about the work; it only covers financial loss from enforcement action |
| Speed | Weeks to months | Usually same day |
| Cost | Council fee (often 150% of building notice fee) plus professional and remedial costs | Typically a one-off premium of tens to a few hundred pounds |
| Key condition | Council must be satisfied work complies | Policy is normally void if you contact the council about the work |
| Safety | Defects identified and corrected | Defects remain unknown |
| Lender and buyer acceptance | Widely accepted; removes the issue permanently | Variable; some lenders and buyers decline it for structural work |
The two are mutually exclusive in practice: approaching the council to regularise typically invalidates an indemnity policy, and a policy only exists because the council has not been approached. For cosmetic or minor items, insurance can be proportionate. For structural work, loft conversions or anything affecting fire safety, a regularisation certificate protects the people living in the property as well as the transaction. Our guide to when to use indemnity insurance looks at the wider picture.
The enforcement landscape changed significantly under the Building Safety Act 2022. Section 39 of the Act rewrote section 35 of the Building Act 1984 so that contravening the building regulations is an offence punishable by an unlimited fine and, on indictment, up to two years’ imprisonment. Crucially, it also amended section 36(4) so that the time limit for a council to serve a notice requiring non-compliant work to be removed or altered rose from 12 months to 10 years. These provisions came into force in England on 1 October 2023 and, according to the commencement information on legislation.gov.uk, were brought fully into force in Wales on 1 July 2026.
The practical consequence is that unauthorised work completed at any point in the last decade remains exposed to enforcement, and where work is dangerous, councils have separate powers with no time limit at all. The old assumption that a breach becomes irrelevant after a year no longer holds.
Regularisation is one of the few building control processes where professional advice before you apply changes the outcome. A building surveyor accredited by a recognised body such as RICS, CIOB or RPSA can:
If you are the buyer rather than the seller, the same surveyor can advise on negotiating a price reduction or retention to cover the cost of regularisation, as explored in our guide to negotiating after a survey.
Survey Merchant is a nationwide panel of independent surveyors, and we match each regularisation case to a suitably qualified, accredited professional with the right specialism, whether that is a building surveyor for a loft conversion, a structural engineer for a removed wall or a valuer where a lender is involved. Here is why homeowners and buyers use us:
Ready to sort out unauthorised building work? Explore our building surveying services or contact Survey Merchant today for a fixed-fee quote.
Survey Merchant provides vetted RICS surveyors across 100+ UK locations at fixed fees:
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→ Expert witness surveyors — CPR Part 35 reports for property disputes
