How it works & data sources

The DPA Checker gives an indicative answer to the question: does this address fall within a Designated Protected Area (DPA), where grant-funded Shared Ownership leases can carry restricted-staircasing or resale provisions?

How a result is produced

You give us a location. Four ways: a postcode or address (with autocomplete); coordinates as latitude/longitude (WGS84) or as easting/northing on the British National Grid; or by dropping a pin on the map. A full postcode or an exact point gives the most reliable result.
We find the location. Postcodes are resolved with postcodes.io, which returns the civil parish, local authority, region and coordinates. Free-text addresses are suggested by Photon (OpenStreetMap), or — if precise address lookup is switched on — by Ideal Postcodes (Royal Mail PAF / AddressBase) for exact house-level results. Coordinates and dropped pins are reverse-looked-up to the nearest postcode to recover the parish.
We identify the civil parish. DPAs in the 2009 Order are defined parish-by-parish, so the civil parish is the unit we match on.
We match it against the legislation. The parish name is normalised and looked up against the schedules of the 2009 Order. Where a parish name occurs in more than one county, we use the geocoded county/region to pick the right one (and flag it if we had to fall back).
We show a verdict and a map. The map pins your location and — where available — outlines the civil-parish boundary from ONS data, so you can see exactly where the result applies.

The four outcomes

in dpa The whole parish is designated (an “entire parish” DPA). Confident result — the entire parish is in the DPA.
partial A “by maps” parish: only part of the parish is designated (typically the rural area, excluding the built-up settlement). Your exact plot may or may not fall inside it, so the official Homes England boundary map is linked on the result — always check it.
not dpa The parish is not listed in the 2009 Order, so it is not a Designated Protected Area.
review An unparished area, or a location we couldn’t confidently classify by parish name alone. These need a manual check against the local-authority maps.

Shared Ownership in a DPA: staircasing & resale

Why does a Designated Protected Area matter? Most grant-funded Shared Ownership homes let you “staircase” to 100% ownership over time. In a DPA — typically rural areas, National Parks and Areas of Outstanding Natural Beauty — the lease can instead cap staircasing (often at around 80%, so you can’t buy the home outright) and add resale restrictions, so the home stays available and affordable for local people. This is what people are really asking when they search “why can’t I staircase to 100%?” or “can I sell my Shared Ownership property?”

Can I staircase to 100% / buy the freehold? If the property is in a DPA, possibly not — your lease may cap staircasing. Check the address here, then read your lease and ask your provider.
Are these homes harder to sell? In a DPA the provider usually has a nomination/right-to-buy-back period and the buyer must often meet local-connection criteria, so resale works differently from an open-market home.
Is the whole area affected? Not always — many parishes are designated only “by maps” (part of the parish). A green/amber result here tells you which case applies.

This explains the indication only — the precise terms are set by your individual lease and the official map. Always confirm with your Shared Ownership provider, a conveyancer and an RICS valuer.

Data sources

Source	What it provides
The Housing (Right to Enfranchise) (Designated Protected Areas) (England) Order 2009 (SI 2009/2098) — legislation.gov.uk	The legal definition of every DPA: the master list of designated parishes (“entire parish” and “by maps”). This is the authoritative basis for every verdict.
Homes England — Designated Protected Areas maps	The official boundary maps (PDFs) for “by maps” parishes, where only part of the parish is designated. Linked directly on partial-match results.
postcodes.io	Free UK postcode lookup: postcode → civil parish, local authority, region, coordinates, and the ONS parish code used to fetch the boundary.
OpenStreetMap (Photon & Nominatim)	Free address autocomplete (Photon) and free-text geocoding fallback (Nominatim), plus the base map tiles shown with each result.
Ideal Postcodes (optional)	Royal Mail PAF / AddressBase address lookup, used only when “precise address lookup” is enabled — to find exact house-level addresses and their coordinates.
ONS Open Geography Portal	Generalised civil-parish boundary polygons (Parishes & Non Civil Parished Areas, Dec 2024), used to draw the parish outline on the result map.

Contains public sector information licensed under the Open Government Licence v3.0. Map data © OpenStreetMap contributors.

Limitations

Indicative guidance only — not legal advice. Results are matched at civil-parish level against SI 2009/2098. They should not be relied on for any transaction without independent verification.

For “by maps” parishes the precise boundary is defined only by the official Homes England map — a parish-level match cannot tell you whether a specific plot is inside or outside the designated area. Always confirm against the official map.

Free address autocomplete via OpenStreetMap/Photon is street/postcode level and lacks most UK house numbers; switch on “precise address lookup” (Ideal Postcodes) for exact addresses. The parish-boundary outline is a generalised polygon for context and is not a legal boundary.

Always take professional advice before relying on a result.

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Spotted something, or want to tell us how you’re using this? We’d love to hear.