Offshore wind - compensating for adverse effects on Protected European Sites: statutory guidance 2026

5. Applying the Compensation Hierarchy

This section describes the new three-tiered compensation hierarchy (Figure 1) that must be applied sequentially when identifying compensatory measures for offshore wind plans or projects.

The compensation hierarchy is also available at this link: http://www.gov.scot/ISBN/9781807752118/documents. Guidance in this section describes the hierarchy in detail and how to apply it.

Tier 1 measures must always be prioritised before considering tier 2 and then tier 3 measures. Movement to a lower tier is only acceptable where appropriate evidence-based justification is provided. Details on circumstances where it is permissible to move down the hierarchy and the evidence required to justify this is in section 5.6.

Examples of measures for each tier are in Annex B.

5.1 Developing Packages of Compensatory Measures

Compensation plans may include compensatory measures which are spread across different tiers. However, the justification for moving down the hierarchy must be provided in each instance where a tier 2 or tier 3 measure is proposed.

Plan or project promoters who are proposing measures across tiers must:

• clearly identify which predicted adverse effects each measure is intended to address, in line with the guidance for the relevant tier; and

• support all proposals with an appropriate evidence-based justification. For guidance on acceptable types of evidence see section 7.8.

Where only part of a tier 1 or tier 2 measure is available due to either feasibility or ecological considerations, the deliverable portion should still be implemented where possible, and any remaining deficit addressed through alternative measures further down the hierarchy.

You are still able to move wholly, or partly, to a tier 2 or tier 3 measure where you can demonstrate that it will deliver a greater ecological benefit to the UK MPA network.

5.2 Accounting for Compensatory Measures with Multiple Benefits

Individual compensatory measures may deliver benefits which extend across tiers. For example, a predator eradication programme may support an impacted seabird species (tier 1) and have the residual benefit of supporting other similar seabird species (tier 2).

For those residual benefits to count towards satisfying a compensation obligation, plan and project promoters must be able to demonstrate that there is appropriate justification to step through the compensation hierarchy. This will be considered on a case-by-case basis.

5.3 Tier 1 – Benefit to the Impacted Feature

For tier 1 compensatory measures, plan or project promoters must provide an appropriate evidence-based justification demonstrating that the proposed compensatory measure will deliver ecological benefit(s) to the feature impacted by the offshore wind plan or project as identified in the Appropriate Assessment, and that those benefits are reasonably proportionate to the predicted adverse effects on the feature(s) that are being compensated for via the measure(s) (see section 6 and section 7.7 for guidance on assessing reasonable proportionality).

When selecting tier 1 measures, plan or project promoters must take account of existing pressures affecting the impacted feature. Measures that do not address a limiting factor would not be appropriate.

For example, the provision of artificial nesting rafts may not be an appropriate tier 1 measure if nesting sites are not a limiting factor on the impacted species.

5.3.1 Tier 1 Location Considerations

Tier 1 measures are not required to deliver benefit at the impacted site, but delivery at the impacted site should be treated as the first preference.

Where compensatory measures are proposed at locations other than the impacted site, plan or project promoters must clearly explain how the proposed location will deliver ecological benefit to the impacted feature, with preference given to the following, in sequence:

• measures that benefit the impacted feature at another European site in a way that strengthens the European site network; and

• measures that benefit the impacted feature in a way that contributes to the wider UK MPA network.

Where interventions at a different location are demonstrably more ecologically effective than measures at the impacted site, priority must be given to European sites supporting the same feature within their biogeographical range in Scotland.

5.4 Tier 2 – Benefit to a Similar Feature

For tier 2 measures, plan or project promoters must demonstrate, using an appropriate evidence-based justification, that the proposed compensatory measure will deliver ecological benefit(s) to feature(s) which are ecologically similar to the impacted feature and that those benefits are reasonably proportionate to the predicted adverse effects on the feature that is being compensated for via the measure(s).

When considering the location of measures, as with tier 1 measure considerations, preference should be given to the following in sequence:

• measures that benefit a similar feature to the impacted feature at a European site in a way that strengthens the European site network; and

• measures that benefit a similar feature to the impacted feature in a way that contributes to the wider UK MPA network.

5.4.1 Determining Ecological Similarity

When determining the ecological similarities of features, relevant considerations include but are not limited to:

• ecological function and ecosystem service provision of the impacted feature and potential benefitting feature, including the ecological processes underpinning those functions and provisions;

• location of the impacted feature and potential benefitting feature and their context/role within the UK MPA network;

• conservation value of the impacted feature and potential benefitting feature, ensuring the benefitting feature is of comparable or greater conservation value;

• spatial and ecological context, including proximity and connectivity to the impacted feature; and

• potential interactions or trade‑offs, including effects on inter‑species balance and competition, of implementing the compensatory measure.

5.5 Tier 3 – Benefit to the UK MPA Network more widely

For tier 3 compensatory measures, plan or project promoters must provide an appropriate evidence-based justification to demonstrate that the proposed compensatory measure(s) will deliver ecological benefit(s) to the UK MPA network more widely and that those benefits are reasonably proportionate to the predicted adverse effects on the feature(s) that are being compensated for via the measure(s).

Ecological benefits may be achieved by targeting broad-scale pressures that impact multiple protected features or sites, or by contributing to the conservation objectives or improving the conservation status of another protected feature within the UK MPA network, which may have no link to the impacted feature.

5.6 Justification for Progression through the Compensation Hierarchy

Progression through the compensation hierarchy must be sequential and based on appropriate evidence-based justifications. Consideration of tier 1 measures must be prioritised before tier 2 measures are proposed. Tier 3 measures may only be considered once tier 1 and tier 2 options have been assessed.

Reasonable efforts must be made to identify appropriate measures. However, a proportionate approach should be taken to assessing the options at each tier of the hierarchy. Plan and project promoters are not expected to explore in detail all possible options before moving down the hierarchy, provided they can demonstrate that reasonable efforts have been made to identify and consider appropriate options at the preceding tier.

A graphical summary of how to move through the Compensation Hierarchy is outlined in Figure 2.

A plan or project promoter may move through the compensation hierarchy if they meet either of the following two tests:

• Availability Test: Robust evidence demonstrates that tier 1 measures are not available, and, where a tier 3 measure is proposed, that tier 2 measures are also not available. Evidence must show that the measures cannot reasonably be delivered, taking account of ecological effectiveness, practicality, legal constraints and deliverability within an appropriate timeframe.

• Greater Ecological Benefit Test: An appropriate evidence-based justification demonstrates that the proposed measure(s) would be effective and deliver a greater ecological benefit to the UK MPA network than a compensatory measure available further up the compensation hierarchy.

These tests are used solely to justify progression between tiers within the Compensation Hierarchy. They are separate from the requirement that all compensatory measures, regardless of tier, must be reasonably proportionate to the predicted adverse effect (see section 6).

5.6.1 The Availability Test

A compensatory measure is considered available where it is anticipated to be feasible, ecologically effective and can reasonably be expected to be practically implemented.

Plan or project promoters must provide an appropriate evidence-based justification to support any conclusion that a compensatory measure is not available. Evidence should be proportionate and robust and may include (but is not limited to) the feasibility and ecological effectiveness considerations set out below:

• A compensatory measure may be considered not feasible where delivery, legal, technical, ecological, or resource constraints prevent it from being implemented effectively. This includes where the measure cannot be secured within an appropriate timeframe (including post‑consent), is technically impractical or legally impossible, cannot achieve the required ecological outcomes within a suitable timeframe, or where costs or resource requirements are disproportionate or cannot be met.

• A measure may be considered not ecologically effective when one or more of the following apply:

  • there is insufficient ecological capacity for the measure to deliver the intended benefit, for example, limited suitable habitat, population ceilings, or environmental constraints;

  • there is insufficient or inadequate scientific evidence, which cannot be addressed by pilot studies or trials, to demonstrate that the measure is likely to deliver the intended ecological benefit for the relevant feature; or

  • there are unacceptable ecological risks or trade‑offs or unmanageable adverse effects, including unacceptable impacts on other designated sites and features, for example, involving ecological trade-offs that would undermine other conservation objectives.

5.6.2 The Greater Ecological Benefit Test

Tier 2 or tier 3 compensatory measures may be proposed in preference to higher‑tier measures where the proposed measure or package of measures would deliver a greater overall ecological benefit to the UK MPA network.

The case for greater ecological benefit must relate to measurable improvements in ecological condition, resilience, or achievement of conservation management objectives, at the appropriate network scale.

Tier 2 measures can deliver ecological benefit to a feature, or group of features that are ecologically similar to the impacted feature, through improvements in condition or resilience and better achievement of conservation and/or management objectives, across a larger proportion of the impacted feature’s SPA or SAC, and/or the European site network, for example by:

• alleviating a relevant pressure across a greater number of SPAs or SACs supporting ecologically similar features;

• improving the resilience of sites supporting ecologically similar features, including to the effects of climate change, across a greater number of European sites;

• benefitting a larger area of habitat that supports ecologically similar features;

• enhancing a greater number or extent of ecosystem services that underpin the ecological function of similar features within the European site network;

• accelerating the recovery of a greater number of European sites supporting ecologically similar features;

• benefitting a greater number or proportion of populations of ecologically similar species; and/or

• restoring or enhancing ecological connectivity across a larger number of European sites in a way that benefits ecologically similar features.

Tier 3 measures may deliver a greater overall ecological benefit at the scale of the UK MPA network by:

• alleviating a pressure across a greater number of MPA sites;

• improving the resilience of the UK MPA network, including to climate change at a larger spatial scale;

• benefitting a larger area of protected habitat within the UK MPA network;

• enhancing a greater number or extent of ecosystem services across the UK MPA network;

• accelerating recovery across a greater number of sites in the UK MPA network;

• benefitting a greater number or proportion of a protected species population in the UK MPA network; and/or

• restoring or enhancing connectivity across a larger number of sites of the UK MPA network.

A measure may also satisfy the greater ecological benefit test where it can be demonstrated and clearly evidenced that it would make a greater contribution to recognised conservation strategies, plans or objectives than could reasonably be achieved through a tier 1 or tier 2 measure. Relevant strategies and plans may include, but are not limited to:

• the Scottish Seabird Conservation Action Plan; and

• the Scottish Biodiversity Strategy.