What is the capacity (kVA) charge on my electricity bill?
The capacity or availability charge on a half-hourly electricity bill is a monthly fee for the network capacity reserved for your site, measured in kVA — you pay for it whether you use it or not. If your maximum demand consistently sits well below your agreed kVA, you can apply to reduce the agreed figure and cut the charge; if you exceed it, excess-capacity penalty rates apply. Both problems show up on the bill, and both are fixable.
Last reviewed 2 September 2026 by Utilities Made Simple · independent, whole-of-market, supplier-paid — how we are paid
Who pays capacity charges?
Half-hourly metered supplies — broadly, larger sites, including many moved onto half-hourly settlement under P272 (Half-hourly vs NHH meters explains which meters these are). If your bill shows lines like “availability”, “agreed capacity” or “kVA”, this guide is about you. Ordinary non-half-hourly SME supplies do not carry a separate capacity charge.
How the charge works
- Agreed capacity (kVA) is the maximum draw your distribution network operator reserves for the site — a figure set when the connection was made or last amended, often decades ago.
- The availability rate (pence per kVA per month, set by your regional network operator) is charged on the full agreed figure, every month, regardless of what you actually use.
- Maximum demand is what you actually peaked at, recorded half-hour by half-hour by your meter — it appears on the bill or in your consumption data.
The two expensive mismatches
| Situation | What it costs you | The fix |
|---|---|---|
| Maximum demand consistently below ~70–80% of agreed kVA | Paying every month for reserved headroom you never touch — common after downsizing, LED refits or machinery changes | Apply to reduce agreed capacity. We check 12 months of half-hourly data first so you keep sensible headroom. |
| Maximum demand exceeding agreed kVA | Excess-capacity charges — since the DCP161 rule change, exceeding your agreed figure is billed at penalty rates, often far above the standard rate, in every month it happens | Increase agreed capacity to the right level, or manage peaks — a proper increase is almost always cheaper than repeated penalties. |
How to check yours in five minutes
- Find agreed capacity / availability (kVA) on the bill.
- Find maximum demand for recent months (on the bill or from your supplier’s half-hourly data).
- Divide one by the other. Utilisation persistently under ~75% suggests a reduction case; anything over 100% means penalties are already being charged.
Before reducing, sanity-check the future: new machinery, EV chargers, electrified heating or a tenant change can all push demand back up — and increasing capacity later can require network studies. Right-size with headroom, don’t just cut to the bone.
We will do the sums for you
Send a bill to the free bill audit and we will pull your utilisation, tell you whether a change stacks up and, with a letter of authority, run the application with the supplier and network operator. Capacity is one of the few bill lines you can cut without switching anything.
Common questions
What does kVA actually measure?
Kilovolt-amperes — apparent power, the total electrical capacity your connection can draw. Think of it as the width of your pipe from the network; the availability charge rents that width, used or not.
How much can reducing agreed capacity save?
It depends on your region's availability rate and the size of the cut. Trimming genuinely unused headroom on a mid-sized site commonly saves hundreds to a few thousand pounds a year — we quantify it from your data before recommending anything.
What is DCP161 in plain English?
An industry rule change that ended the free ride on exceeding agreed capacity: excess kVA is now billed at penalty rates, typically far above the standard availability rate. If your maximum demand tops your agreed figure, every such month costs you extra.
Can I change agreed capacity mid-contract?
Yes — it is an arrangement with the distribution network operator rather than part of your supply contract, applied for via your supplier. Reductions are usually straightforward; increases can need network checks and occasionally works.
Does any of this apply to my ordinary (non-half-hourly) meter?
No — no separate capacity charge applies. Your equivalents to check are the unit rate, standing charge and VAT rate, which our free bill audit covers.
Not sure where you stand? Send us a bill.
Upload a recent bill and a specialist will check your rates, VAT, levies and contract end date against the live market — free, usually the same working day. Prefer email? Send it to info@utilitiesms.co.uk. If your deal is already good, we will tell you to keep it.