How to Read a TNB Bill: Energy, Capacity, Network and AFA

Most people glance at a TNB bill, find the ringgit figure at the bottom, and pay it. But that single number is really five separate charges stacked on top of each other — and once you can name them, you can start managing them. That is the whole promise of this course: you cannot save on a cost you cannot see.

This part decodes the new tariff that took effect on 1 July 2025, replacing the old letter codes (A, B, C1/C2 and friends) that a generation of Malaysian facility managers grew up with. The core idea is simpler than the old system: a bill is the price of fuel plus a delivery and service mark-up, adjusted every month. Learn to read those pieces and the rest of this course — payback, ROI, maximum demand, life-cycle cost — has somewhere solid to stand.

If you are fuzzy on the difference between a kilowatt and a kilowatt-hour, or on how the meter on your wall actually counts, read the Electricity Fundamentals pieces on power versus energy and how electricity meters work first. Everything below assumes you know that energy is measured in kWh and demand is measured in kW.

The old system is gone

Under the pre-2025 structure, your tariff was a letter. Domestic was Tariff A. Low-voltage commercial was Tariff B. Medium-voltage commercial and industrial users lived in the C1/C2/D/E family. To know what you paid, you first had to know your letter.

From 1 July 2025 that classification changed. You are now placed by three attributes instead of one code:

- Voltage level — the voltage at which TNB delivers power to you (more on this below).
- Sector — domestic, commercial, or industrial.
- Pricing option — a single flat rate, or Time-of-Use (ToU), where the per-kWh price changes between peak and off-peak hours.

The bill itself is also broken out more honestly. Instead of one blended rate hiding everything, you now see the components as separate lines.

Three headline components, five charge lines

The new TNB tariff structure 2025 is built from three headline components, which appear on your bill as up to five charge lines:

A useful way to hold this in your head: Generation is the product, Network is the delivery, Retail is the paperwork. The first is what you are buying; the second and third are the mark-up for getting it to you and keeping your account running.

The Base Tariff: the locked-in price

Underneath the Energy, Capacity and Network charges sits the Base Tariff — the price TNB is allowed to charge, fixed for the whole regulatory period so it does not swing month to month. Roughly 70% of the Base Tariff covers generation (making the electricity) and about 30% covers network and operations (delivering it and running the utility).

Think of the Base Tariff as the sticker price agreed with the regulator. It is stable and predictable. The one part of your bill that is designed to move is the AFA.

AFA: the monthly fuel adjustment

Malaysia burns imported gas and coal to make much of its electricity, and it pays for that fuel in US dollars. When global fuel prices spike or the ringgit weakens, generation genuinely costs more than the Base Tariff assumed — and someone has to absorb the gap.

The old mechanism for this was the ICPT (Imbalance Cost Pass-Through), reviewed and reset only every six months. On 1 July 2025 it was replaced by the AFA — Automatic Fuel Adjustment — which updates monthly for both global fuel prices and the exchange rate. Monthly adjustment means smaller, more frequent corrections instead of a twice-a-year shock.

Here is the part worth circling: AFA is currently RM0.00/kWh. When actual fuel costs sit close to the level already built into the Base Tariff, there is nothing to add. For context, the ICPT it replaced had been running at roughly +RM0.16/kWh — a real surcharge on every unit. A zero AFA today is a genuine break, but it is a floating number by design: budget on the assumption that it can rise again.

Voltage decides how you are billed

The single most important fork in the whole tariff is voltage level — the voltage at which TNB hands power over to you. There are three tiers:

- LV (Low Voltage): 230 / 400 V — homes, shops, small offices and light commercial premises. The 230 V is what a single power point delivers; 400 V is the three-phase supply feeding larger LV loads.
- MV (Medium Voltage): 11 / 33 kV — factories, malls, hospitals and larger commercial buildings that take supply at a substation.
- HV (High Voltage): 132 / 275 kV — very large industrial plants connected close to the transmission grid.

The higher your voltage, the closer you sit to the source and the fewer transformation losses TNB incurs to reach you — which is reflected in different rates.

But voltage does more than change the rate. It changes the mechanism. This is the structural point everything else in this course hangs on:

> LV customers pay their Capacity and Network charges per kWh of energy consumed. MV and HV customers pay them per kW of maximum demand.

On an LV bill, every charge line is multiplied by the units you used. On an MV or HV bill, the Capacity and Network components are instead multiplied by your highest sustained rate of draw during the month — your maximum demand, measured in kW, at a rate the RP4 regulatory period sets at roughly RM89.27–97.06/kW. That is a completely different cost driver, and it is where the real money hides for larger buildings. We unpack it in full in Part 4.

A worked LV domestic bill

Let us read an actual Low Voltage domestic bill from the bottom up. The published LV domestic rates (for the first block, up to 1,500 kWh) are:

- Energy Charge: 27.03 sen/kWh
- Capacity Charge: 4.55 sen/kWh
- Network Charge: 12.85 sen/kWh
- AFA: 0.00 sen/kWh (currently)
- Retail Charge: RM10.00 per month (flat)

The total bill for a month is simply each per-kWh rate applied to the energy used, plus the flat retail charge:

$$\text{Bill} = \big(r_{\text{energy}} + r_{\text{AFA}} + r_{\text{capacity}} + r_{\text{network}}\big) \times \text{kWh} + \text{Retail}$$

Take a household that consumes 800 kWh in a month:

- Energy: 800 × 27.03 sen = RM216.24
- AFA: 800 × 0.00 sen = RM0.00
- Capacity: 800 × 4.55 sen = RM36.40
- Network: 800 × 12.85 sen = RM102.80
- Retail: flat = RM10.00

$$\text{Bill} = (0.2703 + 0 + 0.0455 + 0.1285) \times 800 + 10 = \text{RM365.44}$$

Now do the thing almost nobody does — work out the effective rate, the true all-in cost of one unit:

$$r_{\text{effective}} = \frac{\text{Total Bill}}{\text{kWh used}} = \frac{365.44}{800} = \text{RM0.457/kWh}$$

That RM0.457 is the number that actually matters when you evaluate any energy-saving project. The advertised "27.03 sen" is only 59% of what a unit really costs you here — the rest is delivery mark-up and the flat retail charge spread across your consumption. Every time this course computes a saving, it uses a blended effective rate like this one, not the headline energy charge alone. Quoting the energy charge in isolation is the single most common way people overstate — or understate — what a retrofit is worth.

Notice, too, what the AFA line teaches. At RM0.00 it is invisible. But had the old +RM0.16/kWh surcharge still applied, this same 800 kWh month would carry an extra 800 × RM0.16 = RM128 — turning a RM365 bill into RM493, a 35% jump from one line most people never read. That is the difference between watching your bill and being surprised by it.

Why this matters before we go further

You now have the vocabulary the rest of the course depends on:

- A bill is fuel (Generation) plus delivery mark-up (Network) plus service (Retail).
- The Base Tariff is locked; the AFA floats monthly and is currently zero.
- Your voltage level and sector, not a letter code, decide your rates — and voltage decides how you are charged.
- The honest cost of a unit is the effective rate, not the headline energy charge.

For a Low Voltage site, everything is per-kWh, so using fewer units is the whole game. For a Medium- or High-Voltage site, a second, larger game opens up — controlling the peak. That is Part 4.

If watching these five charge lines month-to-month sounds like work, it need not be. Cobler's energy-monitoring platform breaks a facility's consumption down by exactly these components in real time, so you see the Capacity and Network portions of your load as they build, not four weeks later when the bill lands. And if you already know you are on an MV or HV supply, the maximum-demand calculator will give you a first estimate of the per-kW charge we are about to unpack.

The takeaway

A TNB bill is not one number — it is five charge lines telling you what you bought, what it cost to deliver, and how the fuel market moved this month. Under the 2025 tariff, you are classified by voltage, sector and pricing option; the Base Tariff is fixed while the AFA floats monthly (and sits at RM0.00 today, down from an ICPT that once added ~RM0.16/kWh). Read the lines, compute your effective rate, and you have the honest per-unit number every saving in this course is measured against.

Next up — Part 4: Maximum Demand — the RM90-per-kW charge that quietly runs your bill.