Compare and switch
Business ElectricityCompare supplier pricing for your metersBusiness GasFixed and flexible gas contracts explainedBusiness WaterRetailer switching and water cost reviewsBusiness EnergyElectricity and gas managed together
Installations and projects
Business Meter InstallationNew connections, upgrades and smart metersCommercial Solar PanelsRooftop solar for business premisesEnergy BrokersHow brokers work and what we do
Not sure where to start? A comparison covers everything in one go.
Last updated October 2026.
What invoice validation is
Invoice validation is the systematic checking of every energy bill against three things: the contract you signed, the meter data for the period, and the rules that govern how suppliers are allowed to bill. It sounds like bookkeeping. In practice it is one of the more reliable ways a business recovers money, because the error rate on commercial energy billing is persistently high and almost nobody checks.
Our own experience across the bills we review is that a meaningful minority contain at least one error, most of them in the supplier’s favour, and that the errors are rarely dramatic. A standing charge applied at the wrong meter class. A unit rate that did not change when the contract did. VAT at 20 percent on a site that qualifies for 5. Estimated reads that drifted for a year. Individually small, collectively significant, and invisible unless someone compares the invoice to the contract line by line.
- Checks against the contract. Unit rates, standing charges, capacity charges, contract start and end dates, pass-through items.
- Checks against the meter. Read types, consumption plausibility, meter class, MPAN and MPRN details.
- Checks against the rules. VAT rate, Climate Change Levy and relief, back-billing limits, out-of-contract and deemed rates.
- Outcome. Disputed items raised with the supplier, credits and refunds recovered, and a record for the next renewal.
The errors that come up most
Billing errors cluster into a handful of types. Knowing them is most of the skill.
| Error | What it looks like | Why it happens |
|---|---|---|
| Wrong rates after a contract change | Old unit rate or standing charge continues past the new contract start date | Supplier systems not updated when a renewal or switch completes |
| Estimated reads | Long runs of E reads with a large catch-up when an actual read arrives | No smart or AMR meter; access problems; reads not submitted |
| Wrong meter class or capacity | Standing or capacity charge far above what the site’s usage justifies | Meter sized for a previous occupier; capacity never reviewed |
| VAT at the wrong rate | 20% charged where 5% applies, or no declaration on file | Low-usage or charitable status never declared to the supplier |
| Climate Change Levy errors | CCL charged where relief applies, or at the wrong rate | Relief certificate not lodged; rate change not applied |
| Out-of-contract rates | Unit rates 50–80% above market with no contract reference | Termination window missed; contract lapsed |
| Duplicate or misallocated charges | Same period billed twice; charges for a meter that is not yours | Site changes, mergers, meter swaps |
Each of these has its own page in this section, with the detail of how to spot it and how to get it corrected. The common billing errors page is the right place to start.
Have your bills checked
Send us your last twelve months of invoices and we will validate them against your contract and meter data, tell you what we find, and recover anything owed. No obligation.
How validation works
For a single site this is a few hours’ work once a year. For a multi-site estate it is a continuous process, which is why most organisations with more than a handful of meters either resource it internally or outsource it. The multi-site validation page covers how that is set up.
Recovering what you are owed
Suppliers are generally willing to correct clear errors once they are evidenced, and most have a defined complaints and dispute process with timescales. Where a supplier does not resolve a dispute, microbusinesses can take it to the Energy Ombudsman, and larger businesses have contractual and legal routes. The practical limit on recovery is the back-billing rule: suppliers cannot bill domestic and microbusiness customers for energy used more than twelve months ago if the delay was the supplier’s fault, and the same principle shapes how far back overcharges are normally corrected.
That is the strongest argument for validating continuously rather than occasionally. An error found within a year is recoverable; one found three years later may not be. Our refund claims page sets out the process and the time limits in detail, and back-billing rules explains the twelve-month limit and when it applies.
Reading a business energy bill
Validation starts with being able to read the invoice, which is less obvious than it sounds. A business electricity bill carries the MPAN, meter serial, read types, unit rates possibly split by time of day, standing charge, capacity charge, Climate Change Levy, VAT and often several pass-through lines for network and policy costs. Gas bills carry the MPRN, calorific value and the conversion from cubic metres to kilowatt-hours, which is where a surprising number of errors hide. The how to read a business energy bill page walks through both line by line.
Two other pages complete the set: VAT and Climate Change Levy errors, which are the most common recoverable items on small-business bills, and the business energy audit, which looks beyond the invoice at whether the consumption itself is reasonable.
MacIntyre Academies
Quest Academy was locked into its water contract until renewal. An audit, paid only from what was recovered, of its surface water charges recovered £35,364 without switching supplier. The same method applies to energy bills. Read the case study.
Frequently asked questions
What is energy invoice validation?
Checking every energy bill against the contract, the meter data and the billing rules, flagging differences and recovering overcharges. It is distinct from an energy audit, which looks at consumption rather than billing.
How common are errors on business energy invoices?
Often enough to be worth checking. Across the bills we review, a meaningful minority contain at least one error, most of them small and most in the supplier’s favour.
What are the most common business energy billing errors?
Old rates continuing after a contract change, long runs of estimated reads, wrong meter class or capacity charges, VAT at 20 percent where 5 applies, Climate Change Levy charged where relief applies, out-of-contract rates after a lapsed contract, and duplicate or misallocated charges.
How far back can I claim an energy overcharge?
For microbusinesses the back-billing rule prevents suppliers charging for energy used more than twelve months ago where the delay was theirs, and the same principle shapes how far back overcharges are normally corrected. Larger businesses rely on contract terms. Validating within a year is the safe approach.
Do I need a smart meter for invoice validation?
No, but it helps. Actual reads and half-hourly data make the consumption side of validation precise; without them, estimated reads are themselves one of the things being checked.
How does Clearsight Energy charge for invoice validation?
We agree the basis up front, either as part of a wider procurement relationship or as a standalone review. Nothing is charged for a review that finds nothing.
Can you validate water bills too?
Yes, through our sister business, The Business Water Shop, which specialises in water invoice validation and refunds.
What is the difference between invoice validation and an energy audit?
Validation checks that you were billed correctly for what you used. An audit checks whether what you used was reasonable and where it could be reduced. Done together they cover both the price and the volume.
Need help? Get in touch
Call us on 020 8036 5715, or email us, and we will take it from there.