Can your EPC rating fall even though nothing about the property has changed?

In England and Wales, an EPC is a certificate produced under the assessment rules in force when it is lodged, not a promise that the same home will always receive the same band. The practical risk is highest for homes near a band boundary, because a few points can move an E to an F or a C to a D.

Why does an EPC rating drop on reassessment when nothing has changed?

An EPC rating can drop on reassessment because no rule requires the new assessment to reproduce the old score, and in England and Wales the calculation method changed when RdSAP 10 took effect on 15 June 2025. The government approval notice says, “This notice of approval takes effect on 15 June 2025 and is valid until withdrawn by the Secretary of State or superseded.” A lower-E property is therefore exposed: the assessor may be using a different calculation engine, different defaults, and stricter evidence treatment even though the boiler, walls, glazing and insulation are physically unchanged. Industry guidance describes the new evidence approach this way: “RdSAP 10 introduces a hierarchy that prioritises actual evidence over assumptions.” The change is not all one-way: the same RdSAP 10 shift can improve some unchanged homes, including thick solid-brick-wall properties, because “the actual U value of UK solid walls is on average closer to 1.3 W/m²K than the previously assumed 2.1 W/m²K.” If the new certificate comes back F, that is the rating you then have to deal with for letting compliance.

Does getting a fresh EPC now lock in your rating for its full ten years?

A fresh EPC locks in that registered certificate only for up to ten years, and it stops being the operative EPC earlier if a newer certificate for the same building is registered. For England and Wales, the validity rule is not “ten years whatever happens”: the certificate is valid only if “no other energy performance certificate for the building has since been entered on the register.” That means a C-rated EPC obtained now can remain the compliance document through a later methodology change, including a stricter 2027 Home Energy Model, unless it expires or is superseded by a newer EPC. Northern Ireland follows the same cap-not-guarantee structure, requiring that “no other energy performance certificate for the building has since been obtained by or provided to the relevant person.” Scotland is still ten years as at 27 August 2026, with the current rule saying “on the expiry of a period of 10 years from the date on which the document was issued,” but new Scottish regulations are due to cut validity to five years from 31 October 2026. Abodient can hold the EPC certificate against the property and show its expiry alongside other compliance obligations, which matters because registering a newer EPC can change the operative rating before the old ten-year date arrives.

Last reviewed August 2026.

Sources

• MHCLG, “Methodologies for expressing the energy performance of buildings in England and Wales: notice of approval 15 June 2025 — “This notice of approval takes effect on 15 June 2025 and is valid until withdrawn by the Secretary of State or superseded.” Source
• EPC Certificates, “EPC Band Ratings Explained: What Changed under RdSAP 10 in June 2025/2026 — “RdSAP 10 introduces a hierarchy that prioritises actual evidence over assumptions.” Source
• EPC Certificates, “EPC Band Ratings Explained: What Changed under RdSAP 10 in June 2025/2026 — “This change is based on evidence from research showing that the actual U value of UK solid walls is on average closer to 1.3 W/m²K than the previously assumed 2.1 W/m²K.” Source
• Energy Performance of Buildings (England and Wales) Regulations 2012, regulation 9 — “(b)no other energy performance certificate for the building has since been entered on the register.” Source
• Energy Performance of Buildings (Certificates and Inspections) Regulations (Northern Ireland) 2008, Part 2 — “(b)no other energy performance certificate for the building has since been obtained by or provided to the relevant person.” Source
• Energy Performance of Buildings (Scotland) Regulations 2008 — “(b)for all other purposes, on the expiry of a period of 10 years from the date on which the document was issued.” Source
• Energy Performance of Buildings (Scotland) Regulations 2025, regulation 8 — “(a)the expiry of a period of 5 years from the date on which the energy performance certificate was issued,” Source