You probably don't need retrospective planning permission
Most people who Google "retrospective planning permission" don't actually need it. If what you built was already permitted development, the right document is a Lawful Development Certificate — cheaper, faster, and it ends the question forever.
The honest one-line answer
Retrospective planning permission is how you legalise a project that actually needed permission but didn't get it. You're asking the council, after the fact, to approve a development that broke the rules. They can say no — and if they do, enforcement is the next step.
A Lawful Development Certificate (s.191) proves you didn't need permission in the first place. The council issues a document confirming the work was lawful. No approval being asked for; no discretion the officer can exercise. If the facts check out, the certificate is issued.
Those are fundamentally different routes. The first is an application for mercy; the second is a statement of fact. Most householder work that people panic about — loft conversions, rear extensions, outbuildings, garden offices — was almost certainly permitted development when it was built and needs the second route, not the first.
When retrospective planning permission is actually needed
Retrospective planning applications under Section 73A of the Town and Country Planning Act 1990 exist for cases where the development genuinely required planning permission — and didn't get it. In practice that means:
- The work exceeded permitted-development limits. Example: a rear extension 5m deep when the Class A limit is 3m (attached) or 4m (detached); a loft conversion that added more than 40m³ of volume; a two-storey outbuilding.
- The property sits in an Article 4 Direction that removes PD rights for the type of work done.
- The building is listed — PD rights don't apply at all, so any extension or alteration needed listed-building consent plus planning permission.
- The work is in a National Park, AONB, Broads, or conservation area where the relevant PD class is restricted or removed.
- Change of use that wasn't class-permitted — e.g. converting a garage to a separate dwelling.
If none of these apply, retrospective planning permission isn't the right route — and filing one anyway pays a fee the council doesn't have to refund while opening a discretionary decision you didn't need.
When a Lawful Development Certificate is the right route
A Section 191 Certificate of Lawful Existing Development is the correct path if the work either:
- Fits within a permitted-development class (Class A rear extensions within limits, Class B loft conversions within 40m³/50m³ volume and dormer rules, Class E outbuildings within curtilage and height limits). You file an LDC to have the council confirm it was PD.
- Has been in place long enough to become immune from enforcement under the statutory time limits — see below.
The 4-year rule, the 10-year rule, and the 2024 change
Until 25 April 2024, England ran two enforcement immunity clocks:
- 4 years for physical building operations (extensions, outbuildings, conversions) and for change of use to a single dwellinghouse.
- 10 years for other breaches — most changes of use, breach of planning conditions.
Section 115 of the Levelling-up and Regeneration Act 2023 came into force on 25 April 2024 and abolished the 4-year rule in England. From that date, a uniform 10-year rule applies to every breach.
There is a transitional provision that matters a lot if you're asking these questions in 2026:
- If the development was substantially completed before 25 April 2024, the 4-year clock it was already on keeps running. So work from 2019, 2020, 2021, 2022, 2023, or early 2024 can still become immune 4 years after completion under the old rule.
- If the development was substantially completed on or after 25 April 2024, only the new 10-year rule applies.
A rear extension completed in May 2024 (three weeks after the change). The 4-year clock never started. It becomes immune only in May 2034 under the new 10-year rule. Until then, an s.191 LDC on the "just been there a long time" argument won't work — but if it was within permitted-development limits, an s.191 LDC on the PD argument still will.
In Wales, the old 4-year rule was retained. This page covers England only — our service is England-only.
Cost comparison
| Retrospective planning permission | Lawful Development Certificate (s.191) | |
|---|---|---|
| Council fee (householder) | £258 application fee + possible enforcement penalty | £264 statutory fee (half of the full planning fee) |
| Discretionary? | Yes — officer can refuse on policy grounds | No — a question of fact, not merits |
| What it resolves | Retroactively approves the work | Confirms the work was lawful from day one |
| Transfers on sale? | Yes, as part of the planning history | Yes, as a standalone certificate |
| Turnaround | 8 weeks statutory, often longer | 8 weeks statutory, frequently faster |
| Refusal risk | Real — based on current policy | Low if the facts support lawfulness |
| LDC Express all-in (with service) | We don't offer retrospective PP | £613 total (£264 council + £349 service, refunded if refused) |
Evidence you'll need for an s.191 LDC
An s.191 application is fact-driven. The council issues the certificate if you can show, on the balance of probabilities, that either (a) the work was permitted development when it was done, or (b) it has been substantially complete long enough to be immune from enforcement.
The evidence we pull together depends on which argument we're running:
- For the "it was permitted development" argument: dimensions and site plans, specification of materials, photographs, any contractor invoices confirming the build spec. We run each Class's conditions against the facts — A.1(a) through A.1(j) for rear/side extensions, B.1 for lofts, E.1 for outbuildings.
- For the "it's been there long enough" argument: dated evidence covering the full immunity period — Council Tax records, utility bills showing the address in use, dated photographs with metadata, home insurance schedules listing the property configuration, contractor invoices from the build. Statutory declarations from neighbours are accepted by most councils if documentary evidence is thin.
A Statement of Truth signed before a solicitor or commissioner for oaths accompanies the evidence. For s.191 retrospective applications we require wet-ink signature before an independent witness — the digital signature route we use for s.192 proposed-development cases is not sufficient.
What to do if you're mid-sale
The commonest trigger for Googling "retrospective planning permission" is a conveyancer or buyer's solicitor asking about an extension or loft conversion that predates your ownership. Here's the honest decision tree:
- If you have 10+ weeks to exchange: apply for an s.191 LDC. It settles the question permanently for you and every future owner. We turn the draft application around in 3 working days; the 8-week council clock is the remaining wait.
- If you have 4-8 weeks to exchange: still worth applying for an s.191 LDC. If the decision doesn't arrive before completion, ask the buyer's solicitor to accept the pending application as sufficient — many will. If they won't, planning indemnity insurance is a short-term bridge; we cover that trade-off in detail on the LDC vs indemnity page.
- If you have less than 4 weeks and the buyer's solicitor has explicitly said "indemnity is fine": take the indemnity for speed. You or the next owner can resolve it with an LDC later.
- If the work genuinely wasn't permitted development and was done after 25 April 2022 (so not immune on the 4-year rule or the new 10-year rule): this is one of the narrow cases where retrospective planning permission is actually on the table. Speak to a local planning consultant — we don't file retrospective planning applications. We'll say so at the intake stage if this is your situation.
Common questions
Can the council refuse a Lawful Development Certificate on policy grounds?
No. An LDC is a factual determination. If the work was permitted development, or has been immune for long enough, the council must issue the certificate. They can refuse on the facts — saying the evidence doesn't support lawfulness — but not on the grounds that they don't like the development.
If the council refuses an LDC, can they then serve an enforcement notice?
They can if the work is still within the enforcement period. That's one reason we take the evidence stage seriously — we won't file an s.191 application we don't think will succeed. If our intake flags that the facts don't support lawfulness, we recommend a different route at the start, not a refused application.
Is an LDC the same as a Certificate of Lawfulness?
Yes. "Lawful Development Certificate" (LDC) and "Certificate of Lawful Use or Development" (CLEUD/CLOPUD) are used interchangeably. Section 191 covers existing development; Section 192 covers proposed development. Both are issued under the same council process.
What happens if I did the work myself and I'm not sure it was within permitted development?
Start with our intake — it walks through the class conditions in plain English and flags anything risky. If the dimensions or position don't support a PD argument, we'll tell you before you pay, not after.
Does the LDC cover building regulations too?
No — those are separate. An LDC proves planning lawfulness. Building Regulations compliance is handled separately through the local authority's Building Control team, and a missing Building Regs completion certificate is resolved with a Regularisation Certificate. We can point you to the right team; the two can run in parallel.
Our honest take
Half the retrospective planning permission searches we see started as a conveyancer email with three letters in it: LDC. If that's you, don't Google your way through it — 5 minutes on our intake wizard will tell you whether an s.191 LDC is the right route, what evidence we need, and whether the timeline fits your transaction. If it doesn't, we'll say that and point you somewhere that does.
Start the 5 minute qualifier →Related reading
- What is a Certificate of Lawfulness? — the full hub page.
- Conveyancer asked for an LDC — what now? — for panic-mid-sale scenarios.
- LDC vs planning indemnity insurance — honest comparison of the fast-bridge option.
- LDC cost breakdown — £613 total, refund if refused.
- How LDC Express works — 4 steps from intake to certificate.