Related Posts by Categories and Tags (formerly CRP Taxonomy Tools) is an extension for Contextual Related Posts that adds another degree of related posts matching by adding the option to restrict these related posts to the same category, tag or custom taxonomy.

Additionally, you can also disable the contextual matching engine either on posts/pages or on only custom post types.

The plugin adds its settings under the General and the List tuning tabs respectively in the Contextual Related Posts settings page.

Related Posts by Categories and Tags - General settings

Related Posts by Categories and Tags – General settings

Related Posts by Categories and Tags - List tuning

Related Posts by Categories and Tags – List tuning

Requires Contextual Related Posts v2.6.0 or higher.