An EPC is valid for 10 years but a new EPC assessment before then may be a good idea. If yours has not expired, you are not legally required to get a new one, but there are specific situations where commissioning a new assessment makes real financial and practical sense. There are also situations where it is a waste of money. This guide helps you work out which category you are in.
When You Have No Choice: Legal Requirements
Before getting to the question of whether you should get a new assessment, confirm whether you legally need one.
You must have a valid EPC when:
Selling your property. An EPC must be commissioned and available before a property is marketed for sale. If your existing EPC has expired, more than 10 years since it was issued, you need a new one.
Letting a property. Landlords must have a valid EPC before marketing a rental property to tenants. The EPC must show a rating of E or above (or a registered exemption). If your rental EPC has expired or the property has never had one, you need a new assessment.
A newly built or substantially altered property. New builds require an EPC as part of building regulations sign off.
Check the EPC Register at epcregister.com. Enter the property address and you will see whether a valid EPC exists, when it was issued, and when it expires. Any property that has been on the register within the last 10 years does not legally need a new assessment for a sale or letting, as long as the circumstances covered in the register certificate still broadly apply.
When a New Assessment Is Worth Getting Voluntarily
You Have Made Significant Improvements Since the Last Assessment
An EPC captures the property at the time of assessment. If you have installed loft insulation, cavity or solid wall insulation, double glazing, a new boiler, solar panels, or underfloor heating since the last certificate was issued, none of these improvements are reflected in your existing EPC.
This matters for several reasons:
The EPC may understate your property’s performance. A rating of E on an old certificate for a property that now has full loft insulation, a new boiler, and double glazing is inaccurate. The actual rating is probably C or D.
A higher rating can affect your mortgage or sale price. Lenders increasingly factor EPC ratings into mortgage product availability. Some green mortgage products offer preferential rates for A or B rated properties. A more accurate certificate may open better financing options.
For landlords, a higher rating affects compliance status. If an existing certificate shows E or below but improvements since that assessment would now produce a D or C, a new certificate demonstrates compliance with MEES without the need for an exemption.
The question is how confident you are that the improvements would produce a meaningfully better rating. If you have replaced windows, topped up the loft, and installed a new boiler since a D certificate was issued, a new assessment will almost certainly show C. If you have done relatively minor work, the improvement may not cross a band boundary.
A scenario analysis from an experienced EPC assessor, asking them to estimate the likely rating given the improvements made, can help you decide whether a new assessment is worth commissioning before paying for it.
Your EPC Was Issued Before June 2025
The RdSAP 10 methodology update in June 2025 was the most significant change to EPC calculations in over a decade. Properties assessed under the previous methodology (RdSAP 9.94) may score differently under RdSAP 10, higher or lower depending on their characteristics.
Properties likely to score better under RdSAP 10:
- Solid brick properties with walls thicker than 280mm (revised U value assumption)
- Mid floor flats and mid terrace properties (revised heat loss assumptions for shared elements)
- Properties where documentation of improvements is now available that was not available at the previous assessment
Those that may score differently (not necessarily worse):
- Properties where the previous assessor used generous default assumptions that RdSAP 10 no longer permits
- Properties where the heating system details could not be verified and the new methodology applies a lower default
If your property falls into one of the categories likely to benefit from RdSAP 10, and you are close to a band boundary, particularly the D to C boundary, a new assessment is worth considering.
You Are Planning Improvements and Want an Accurate Baseline
If you are about to spend money on insulation, glazing, or heating upgrades, you want to start from an accurate picture of where the property currently stands. An old EPC, particularly one from before RdSAP 10, may not give you that.
A current assessment provides:
An accurate current score and band. What is the property actually rated at today, under the current methodology?
An accurate potential score. What could the property achieve if all recommended measures were implemented?
A current recommended improvements table. Which measures does the assessor recommend, in what order, and what is their estimated individual impact?
This information directly shapes which improvements to prioritise and in what order. Spending money on improvements guided by an old certificate is less efficient than spending money guided by a current one.
You Are a Landlord Planning for the 2030 MEES Deadline
Landlords need to achieve EPC band C by 1 October 2030. A new assessment in 2026 or 2027, before the Home Energy Model methodology change expected in late 2027, gives you:
An accurate picture of the current rating. Where does each property in your portfolio actually sit under RdSAP 10?
A clear gap to C. How many points does each property need to reach C, and which measures deliver those points most cost effectively?
The ability to plan and phase improvements. Rather than rushing improvements in 2029 and 2030 when installer availability will be constrained and prices elevated, you can commission work now at your own pace.
The strategic option of locking in a C before HEM. A valid EPC C issued before October 2029 under the current methodology is treated as compliant for up to 10 years. Getting assessments and improvements done now preserves this option.
When a New Assessment Is Not Worth It
Your Existing Certificate Is Recent and Nothing Has Changed
A certificate issued in the last two or three years under RdSAP 10 (post June 2025) accurately reflects the property. If you have not made any significant improvements since then, a new assessment produces essentially the same result at a cost of £60 to £120 for no benefit.
You Are Commissioning Improvements and the Assessor Will Come Back Afterward
If you are about to install significant improvements, solid wall insulation, a heat pump, solar panels, there is no point commissioning an assessment now when the certificate will be outdated within months. Commission the improvements, then get a new assessment once they are complete to capture the improved rating.
The exception is if you need an accurate current baseline to plan what improvements are needed. In that case, a pre improvement assessment is useful planning information even if you will commission another one after the works.
The Improvement to Your Rating Would Be Marginal
If you have made minor improvements since the last assessment, draught proofing, a new programmer, LED lighting, and these are unlikely to move the rating by more than a point or two, a new assessment is not going to produce a meaningfully different certificate. Save the money.
What to Expect From a New EPC Assessment
A domestic EPC assessment typically takes 30 to 60 minutes for a standard property. The assessor visits the property and records:
- Wall, roof, and floor construction
- Heating system type, make, model, and controls
- Hot water provision
- Window glazing type and condition
- Presence and depth of insulation in loft and walls
Under RdSAP 10, the assessor uses a hierarchy that prioritises documented evidence over default assumptions. Bring out any documentation you have, boiler installation certificate, insulation completion certificates, FENSA window certificates, before the assessor arrives.
The assessor enters the data into approved SAP software, calculates the rating, and lodges the certificate on the national EPC Register. You receive a copy. The certificate appears on the public register within a few days of lodgement.
How Much Does a New EPC Assessment Cost?
EPC costs in 2026 range from approximately £60 to £120 for a standard domestic property, depending on the property size and the assessor’s location and pricing. Larger properties take longer to survey and cost more.
Shop around, but do not choose purely on price. An assessor who spends 20 minutes in a large property has not assessed it properly. Check that the assessor is accredited on the EPC Register’s accredited assessor search before appointing them.
Frequently Asked Questions
Can I use an existing EPC if I am selling my property? Yes, if it is less than 10 years old and lodged on the national register. You do not need a new assessment unless the existing certificate has expired.
Will a new EPC definitely show a higher rating if I have made improvements? Not definitively, it depends what improvements you have made and how they affect the calculated energy performance. Significant improvements such as full loft insulation, cavity wall insulation, or a new boiler are very likely to improve the rating meaningfully. Minor improvements may make little difference.
Can I choose which assessor to use? Yes. You can commission an EPC assessment from any accredited domestic energy assessor. Find accredited assessors through the EPC Register or through accreditation bodies such as Elmhurst Energy, Stroma, or ECMK.
How long does it take to get an EPC? Most assessors can complete the survey and lodge the certificate within a few days of the visit. In busy periods, appointment availability may extend this. For sale or letting situations with a deadline, book early.
Does the EPC assessor check if my insulation is actually there? The assessor records what is visible and what can be evidenced through documentation. They do not open walls or carry out invasive inspections. Where insulation is not visible and no documentation exists, the assessor may record the wall or floor as uninsulated. Keep all installation certificates to ensure improvements are correctly recorded.
Costs and methodology information correct as of April 2026. The Home Energy Model is expected in late 2027 and will introduce a new assessment framework, monitor government guidance for updates.