The Residence Nil-Rate Band (RNRB) is an additional Inheritance Tax threshold available when a main residence is left to direct descendants. It applies on top of the standard nil-rate band and can also be transferred between spouses or civil partners.
Legal Reference
Introduced by the Finance Act 2015 and applied through amendments to the Inheritance Tax Act 1984.
The RNRB currently provides up to £175,000 in additional tax-free allowance if eligibility criteria are met, including ownership of a qualifying residence and a direct lineal descendant as beneficiary.
Sources
Wikipedia – https://en.wikipedia.org/wiki/Nil_rate_band
Wikidata – https://www.wikidata.org/wiki/Q7036811
Gov.uk – https://www.gov.uk/guidance/inheritance-tax-residence-nil-rate-band
Knowledge Graph – https://www.google.com/search?kgmid=/m/03yn93c
DBpedia – http://dbpedia.org/resource/Nil_rate_band
Product Ontology – http://www.productontology.org/id/Nil_rate_band