Your September electricity bill is going to be smaller. Quite a lot smaller.
Eskom’s high-demand season ended on 31 August. Winter rates are gone until June.
You will open that bill and feel relief.
One line on it will not have moved. Same rand value as July. Same as August.
That line is your notified maximum demand charge. Most owners have never seen the number it is calculated from.
Why didn’t my whole bill drop in September?
It is not a billing error.
It is not the April increase either. That was 8.76% for Eskom-direct customers. It landed five months ago, and it lifted every charge, not one.
And it is not your demand charge. That one does fall, hard.
On Nightsave Urban the energy demand charge drops from R332.91 per kVA a month to R77.88. On Megaflex the peak energy rate falls from 720.19c a unit to 298.89c.
Add the network demand charge of R26.29 and the seasonal difference is stark:
- Winter: R332.91 + R26.29 = R359.20 per kVA per month
- Summer: R77.88 + R26.29 = R104.17 per kVA per month
Almost everything drops on 1 September. One charge does not.
What is notified maximum demand?
The charge that stays put is your distribution network capacity charge. It is billed on your notified maximum demand, or NMD.
Your NMD is the capacity you asked Eskom to hold open for you. It is measured in kVA. It was written into your supply agreement, often years ago, often by someone who has since left.
Think of a restaurant booking. You reserve a table for forty and twelve people arrive. The kitchen was staffed for forty, and the bill reflects that.
Eskom reserves network capacity the same way. You told them how much to hold. They built and maintained it. You pay for it whether you draw it or not.
The rate is R39.13 per kVA per month, excluding VAT.
That is R45.00 including VAT, or R469.56 per kVA per year excluding VAT.
Why doesn’t this charge fall in summer?
Here is the part that catches people.
The charge is not billed on your NMD alone. It is billed on what Eskom calls annual utilised capacity.
The Schedule of Standard Prices defines it. Here is Eskom’s own wording:
“the higher of the notified maximum demand (NMD) or the maximum demand … registered during a rolling 12-month period.”
Read that again. The higher of the two. Measured across a rolling year.
So your single worst half-hour of the last twelve months is still setting this charge today.
And that half-hour almost certainly happened in June, July or August. Winter is when the heating ran, the shifts overlapped, and every compressor restarted together after a stoppage.
That peak does not expire tomorrow. It follows you into summer. It keeps counting until it rolls out of the twelve-month window, some time next winter.
Your energy bill falls on 1 September. This charge stays anchored to a winter you have already left.
What is unused capacity costing you?
Put a number on it.
Say your supply agreement specifies 500 kVA. Say your highest recorded demand over the last twelve months was 400 kVA.
That leaves 100 kVA of capacity you reserved and never used.
R39.13 × 100 kVA = R3,913 per month, excl VAT
R3,913 × 12 = R46,956 per year, excl VAT
That is a bakkie payment. For a pipe you are not filling.
The arithmetic scales linearly, which makes it easy to check your own position. Every unused kVA costs R39.13 a month, or R469.56 a year excluding VAT.
Now the honest part. Recovering it is neither free nor fast.
Why this matters more next year than this year
There is a reason not to leave this on the pile until winter.
NERSA miscalculated Eskom’s regulatory asset base by R54.7 billion. The regulator decided to recover that error through tariffs across three years.
The instalment inside your current tariff is R12 billion. Next year’s instalment is R23 billion.
Without that recovery, this year’s increases would have been 5.36% for Eskom-direct customers instead of 8.76%.
So the charge you are looking at is the cheap version. Every rand of capacity you are not using gets more expensive in April.
How to check your NMD this week
Step one costs you nothing. Find your NMD. It is stated in your supply agreement. It is usually printed on your bill beside the capacity charge line.
Step two. Ask Eskom for twelve months of maximum demand readings. Pull them from your meter data if you already log it. You want the highest kVA recorded in each month.
Step three. Take the highest of those twelve figures. That is your real operating ceiling. Subtract it from your NMD.
The gap is capacity you are paying for and not using.
Step four. Read the next section before you apply for anything. This decision is much easier to make than to reverse.
Step five. Apply in writing to Eskom.
What do you give up by cutting your NMD?
Eskom’s published NMD rules ask for written notice, and twelve months is the normal requirement. They say a shorter period, down to three months, will not be unreasonably withheld if you can motivate it.
You also cannot drop below your highest recorded demand of the last twelve months. Not without a supporting reason, such as a plant closure, an operational change, or load management equipment you have actually installed.
Going back up is harder than coming down. Eskom’s own guidance says a supply increase can take up to six months and carries a cost.
So do not cut to the bone. If you are planning a new production line, a second shift, or another cold room, leave headroom for it.
There is also a penalty for getting it wrong. Exceed your reduced NMD and Eskom charges an excess fee. It is based on the kVA you went over and the number of months you did it, across a rolling twelve months.
Cutting your NMD is a one-way door with a slow handle. Size it once, properly.
Who this post is not for
If your NMD already sits close to your real winter peak, there is nothing here to reclaim. Go and check your power factor instead. That is the other charge hiding on your winter bill.
If you are on Businessrate, stop reading. Businessrate carries no rand-per-kVA capacity charge at all. Those supplies are 100 kVA or smaller and the structure is genuinely different.
And if a municipality bills you rather than Eskom, your tariff is theirs, not Eskom’s. The principle usually carries across. The rates on this page do not.
Questions we get asked
Will a battery reduce my network capacity charge?
Not by itself. A battery cuts the peak you draw, which reduces the network demand charge of R26.29 per kVA a month. The capacity charge is billed on reserved capacity, so it only falls once you formally reduce your NMD. Shave the peak first, then apply.
How do I find my notified maximum demand?
It is stated in your Eskom supply agreement. It is usually printed on your monthly bill beside the capacity charge line. If you cannot locate it in either document, Eskom’s customer contact centre can confirm the current value.
Does my NMD reset when the season changes?
No. The season changes your energy rates and your demand rates. It does not touch your reserved capacity. Annual utilised capacity runs on a rolling twelve-month window, so a June peak still counts in December.
What happens if I cut my NMD and then exceed it?
Eskom charges an excess fee. It is calculated from the kVA above your NMD and the number of months you exceeded it, over a rolling twelve months. A large enough overshoot can also reset your billed capacity upward.
Is it worth doing for only 30 kVA of headroom?
Do the sum before deciding. 30 × R39.13 = R1,173 a month, or R14,076 a year excluding VAT. Whether that justifies the notice period and the lost flexibility is a commercial judgement, not an engineering one.
Where do I find the exact rates for my own supply?
Eskom publishes them annually in the Schedule of Standard Prices. Rates vary by voltage, by distance from the transmission zone, and by whether you are a local authority. Match your band before modelling anything.
The number is worth an afternoon
Most of this you can do without us. Find your NMD. Pull the readings. Do the subtraction.
If the gap is small, you have spent an afternoon and gained certainty.
If the gap is large, you may want a second pair of eyes. We can check the load data and the supply agreement before you write to Eskom.
Still working out why your bill is what it is? Start there instead.
Rates quoted are from Eskom’s Schedule of Standard Prices for the 2026/27 financial year, effective 1 April 2026, on the non-local-authority basis for supplies of 500 V and above but below 66 kV, within 300 km of the transmission zone. Your own band may differ — check the Schedule against your bill. NMD process detail is from Eskom’s published notified maximum demand rules and Eskom Energy Advisory Services guidance; those rules are subject to review, so confirm the current version before you plan around the notice periods. Nothing here is tax or financial advice.
