Welsh language impact and when an assessment is needed

This article is about the planning system in Wales. Decision makers in Wales must have regard to considerations relating to the use of the Welsh language, so far as they are material to the application, because the Planning (Wales) Act 2015 amended section 70 of the Town and Country Planning Act 1990 to that effect. There is no equivalent duty in England. The practical consequence is that a housing scheme in a community with a high proportion of Welsh speakers may be asked for a Welsh language impact assessment, sometimes called a linguistic impact assessment, before a local planning authority will determine it.

Whether you need one depends almost entirely on the local development plan. The statutory duty says the language is capable of being material. It is the plan that says at what scale and in which places an assessment is expected.

Where the duty to consider Welsh language sits in policy

Three layers stack up. The Welsh Language (Wales) Measure 2011 gives the language official status in Wales and created the office of the Welsh Language Commissioner. Planning Policy Wales, the national policy document, treats the language as part of the social and cultural wellbeing that the planning system is meant to support, and expects development plans to consider the effect of growth on Welsh-speaking communities. Then the local development plan translates that into policy with thresholds attached.

The duty bites on the decision, so an authority cannot refuse to consider language effects on the basis that the plan is silent. In practice a silent plan makes the point much harder to run, because there is no adopted policy against which to judge harm.

The technical advice that frames the assessment

Technical Advice Note 20 deals with planning and the Welsh language, and it is the document officers reach for. Its broad position is that effects on the language are a consequence of the scale, phasing, type and location of development rather than something that can be assessed in the abstract, and that plan making is where the main work should be done. For individual applications it expects proportionate assessment where the development plan identifies the need.

The advice also warns against treating the language as a reason to resist all development. Welsh-speaking communities need housing, jobs and services, and an assessment that concludes a scheme should not proceed because it brings people into an area is unlikely to carry weight on its own. The question is the balance of effects, and whether phasing and mitigation can change it.

Thresholds and triggers used by Welsh authorities

Thresholds sit in local development plan policy, not in national guidance, and they differ. The pattern across the north west and west of Wales, where the proportion of Welsh speakers is highest, is a tiered approach: a short Welsh language statement for smaller schemes and a fuller impact assessment above a stated number of dwellings or a stated site area, with the trigger sometimes narrowed to sites outside defined settlement boundaries.

Do not guess the figure. Read the adopted development plan policy and any supplementary planning guidance the authority has published on the language, and ask at pre-application which document the officer expects. Where a joint plan covers two authorities, the policy and the threshold are the same across both, which is useful when a site straddles a boundary.

Other triggers appear too. Change of use affecting a community facility, loss of a shop or school, large employment proposals and holiday or second home accommodation can all engage language policy where the plan says so.

What a linguistic impact assessment contains

The structure that authorities accept is reasonably settled:

1. A baseline for the community, drawn from census data on Welsh language skills at the smallest geography available, plus school Welsh-medium provision and the use of the language in local services.
2. A description of the development, its phasing, tenure and housing mix, and the market it is aimed at.
3. An assessment of population change, including likely in-migration and the retention of local young people.
4. The effect on the community's linguistic balance, expressed as a reasoned judgement rather than a false precision.
5. Effects on Welsh-medium education capacity and on community facilities where the language is used.
6. Mitigation, phasing and monitoring.
7. A conclusion that addresses the relevant development plan policy directly.

Avoid the two failure modes. One is a statistical exercise that produces a percentage change in speakers with no stated method. The other is a page of assurances with no baseline at all.

Mitigation measures that authorities accept

Mitigation tends to be about pace, tenure and visibility rather than anything exotic. Phasing the release of plots so that growth is absorbed over years rather than months. Affordable housing in tenures that help local households stay. Welsh street and development names agreed with the authority's naming process. Bilingual signage and marketing. Contributions towards Welsh-medium school places where the education authority identifies a capacity issue. Support for a community facility where the language is used daily.

These are secured by condition or by a planning obligation, which means they have to meet the usual tests of necessity and relationship to the development. A contribution towards general Welsh language promotion with no link to the scheme is unlikely to survive scrutiny.

Phasing and the cumulative question

Cumulative effect is where most arguments happen. A scheme of modest size can look harmless alone and material when set against three other commitments in the same village. Authorities assess the plan's overall growth against the community, so an applicant should check the housing trajectory and the extant permissions in the settlement before arguing that their scheme is too small to matter.

Phasing is the most persuasive mitigation available, and it is also the most commonly resisted by applicants because it affects cashflow. A phasing condition tied to the completion of earlier plots is a reasonable ask where the plan policy is engaged.

Evidence sources for community language data

Use published sources and name them. Census results on Welsh language skills are published at output area and ward level, which is small enough to describe a village rather than a county. Welsh Government statistical releases give more frequent survey estimates at authority level, useful for trend rather than for local detail. The education authority's Welsh in Education Strategic Plan gives school capacity and Welsh-medium provision. The authority's own plan evidence base will usually contain a language background paper.

Be straight about limitations. Survey estimates and census counts measure different things and are not interchangeable, and small-area counts carry rounding. An assessment that acknowledges that reads better than one that does not.

Where PlanScope is used for a Welsh application, treat the output as England-grounded drafting that needs the national policy framework for Wales checked by whoever reviews it, because the drafting is based on the National Planning Policy Framework and English local plans. The Planning Statement and supporting documents still need a Welsh policy read-through, and a reviewer from the professional directory can do that. Elsewhere in the devolved systems the differences run deeper still, from the hierarchy of developments in Scotland to the two-tier arrangement in Northern Ireland.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.