How long a commercial EPC lasts and when to get a new one

Valid and wrong at the same time

Change the lighting, replace the boiler, insulate the roof, and the certificate on the register says exactly what it said before. It remains valid. It also now understates the building, in public, to anyone who looks it up.

That matters at precisely the moments a certificate matters: a letting, a sale, a refinance, a MEES question. Paying to reassess a building you have improved is usually the cheapest part of the whole improvement project, and it is the step most often forgotten once the contractor has left.

When to reassess early

After any meaningful improvement works, as the final step of the project rather than an afterthought.
Before marketing the property for sale or letting, so the public record reflects the building accurately.
Before a lender or investor looks at it, for the same reason.
Where the current certificate was produced with poor access or missing documentation, and defaults were applied that you can now evidence away.
Where the building has changed use or been subdivided, because the assessment basis may no longer match the property as let.

The methodology moves too

The modelling methodology and the factors inside it are updated periodically. That means the same unchanged building can produce a different rating when it is reassessed, in either direction, without anything physical having happened.

It is a reason not to assume a reassessment will confirm what you expect, and a reason to model before committing capital on the basis of an old certificate.

Subdivision is the quiet trap

A certificate covers the property as assessed. Split a unit into two, or combine two into one, and what is on the register may no longer correspond to what you are letting. That is a problem that surfaces at the letting, which is the worst moment to discover it.

If the demise has changed, the certificate position needs checking before the property is marketed.

Questions we get asked

How long is a commercial EPC valid for?

Certificates run for a fixed period from lodgement. We are not printing a figure here because it is a number people act on and it should be confirmed for your situation. The more useful question is usually whether the certificate still describes your building.

Do I need a new EPC after improvement works?

The old one stays valid, but it also still shows the old rating, so the improvement is invisible to anyone looking at the register. Reassessing is normally the cheapest part of the project and should be planned into it rather than remembered afterwards.

Can the rating change without changing the building?

Yes. The modelling methodology and the factors within it are updated periodically, so the same unchanged building can assess differently, in either direction. It is a reason not to assume a reassessment will confirm the old result.

What if I have split or combined units?

The certificate covers the property as it was assessed. If the demise has changed, what is on the register may not correspond to what you are letting, and that needs checking before marketing rather than at the letting.

Last updated 8 October 2026.