Acari are one of the most abundant and functionally important mesofauna taxa in forest soils, yet their potential as indicators of soil health remains underexplored due to taxonomic constraints. This study uses data from the UK government’s ongoing National Capital Ecosystem Assessment (NCEA) programme to characterise Acari communities across forest and soil types at a national scale, and to evaluate their suitability as indicators of forest soil condition. Standardised soil cores (10 cm depth, 5 cm diameter) were collected from 58 plots in England and Scotland between 2022-2024 adapting the standardised European BioSoils design into the NCEA monitoring framework. Forest plots spanned conifer, broadleaf and mixed stands on a range of soil types. Acari were extracted from soil cores via Tullgren funnels, stored in molecular graded ethanol and identified to the finest taxonomic resolution possible (species, family) prior to destructive metabarcoding analysis. A “higher taxon approach” (family-level community pattern analysis) has the potential to clarify and generalise patterns observed at the species level, but its effectiveness in UK forest soils remains to be tested. We expect forest Acari communities to be dominated by Oribatida, reflecting the high organic matter content and stable litter inputs typical of forest soils compared with other ecosystems. Across the national network, Acari abundance and diversity are likely to vary with forest type, with broadleaf and mixed stands supporting higher richness and more even communities than conifers, and showing shifts in the relative abundance of Oribatida, Prostigmata and Mesostigmata. Multivariate analyses are expected to reveal compositional differences amongst forest and soil types, as well as significant relationships between Acari communities and key physico-chemical variables (e.g., pH, organic carbon and bulk density) and structural forest attributes (e.g., tree species diversity, litter availability). From these patterns, we aim to identify bioindicators associated with soil quality and structural complexity in forests. Overall, this work will provide the first in-depth national-scale assessment of forest soil Acari in the UK and will evaluate their potential inclusion in national routine soil health assessments and long-term ecosystem monitoring, including the feasibility of higher-taxon surrogates to overcome taxonomic constraints.