An electricity bill looks like a receipt written in a language nobody taught you. There is a consumer number, a reading box, slab headings, a fixed charge, a fuel charge, a duty — and, somewhere near the bottom, the one number you actually care about. The quiet truth is that the bill is fully predictable: every line is defined by state regulation, and once you know what each one means, you can check the whole document for errors in about five minutes.
This guide walks down the bill in the same order the printer lays it out — top to bottom — and finishes with a short audit you can run before every payment. If your state prints a line under a slightly different name, the explanation here still applies: most DISCOMs run the same set of charges, just with different labels.
The Three Numbers That Explain Everything
Ignore the rupee figure for a minute. Three numbers at the top of the bill tell you most of what matters: the consumer number, the category, and the sanctioned load. The consumer number is your account with the DISCOM — quote it in every payment, every complaint, every name transfer. The category decides which price table applies to you: domestic, commercial, agricultural and industrial tariffs are priced very differently, and being billed in the wrong category is one of the most common silent errors on Indian bills. A commercial category applied to a home can roughly double the energy charge.
The sanctioned load is the size of your connection in kilowatts, and it decides the fixed charge — and, in some states, the slab structure itself. The load printed on the bill is the load you applied for, not necessarily the load you use, which is why upgrading a 1 kW connection to 3 kW for an air-conditioned home changes the fixed charge even when your units stay flat. Load, category and consumer number are the identity of the bill; everything below is arithmetic built on top of them. A fuller look at the load — and how changing it changes your bill — is in our sanctioned load guide.
The Reading Box: Where the Units Come From
The reading box holds the previous reading, the current reading, and the difference — the units you are billed for that cycle. Check one thing before comparing anything else: whether the readings are marked "A" for actual or "E" for estimated. An estimated bill is the DISCOM's best guess at your usage, usually an average of recent bills, and the next actual reading will settle the account — which is exactly why a bill that follows a run of estimates often arrives with a jump.
Also check the number of days. A 45-day bill legitimately carries about half again the units of a 30-day bill from the same home. Divide the billed units by the days to get units per day, then compare it with your average over the last six to twelve bills: it is the single best number for separating a genuine change in usage from a billing artefact. If a reading looks impossible — lower than the previous one, or wildly off — read our guide on catching meter reading errors before you pay.
Slab Pricing: Why the Same Units Cost Different Amounts
Indian domestic tariffs are slabbed: the first so many units are cheap, the next block costs more, and the top block costs the most. The energy charge line is the sum of each slab's units multiplied by its rate — not one rate applied to the whole consumption. This is the line where most personal arithmetic goes wrong, because a 400-unit bill is not four times a 100-unit bill; it is the cheap slab, plus the middle slab, plus the expensive slab, added in slices.
| Line | Units | Rate | Amount |
|---|---|---|---|
| Energy: 0–200 units | 200 | ₹4.00/unit | ₹800 |
| Energy: 201–400 units | 200 | ₹6.50/unit | ₹1,300 |
| Energy charge subtotal | 400 | — | ₹2,100 |
| Fixed charge | — | flat | ₹100 |
| FAC (fuel adjustment) | 400 | ₹0.55/unit | ₹220 |
| Electricity duty | — | 5% of ₹2,520 | ₹126 |
| Total | — | — | ₹2,546 |
The same 400 units under a four-slab structure would split differently, but the principle is identical. Your state's exact slabs live in its regulator's latest tariff order, and the tariff directory on this site summarises the tables for every major state.
Fixed Charges and the Sanctioned Load
The fixed charge is a flat monthly fee for the connection itself — for keeping your sanctioned load available whether you draw it or not. In most states it is set by load slab, so a 2 kW connection pays more than a 1 kW connection regardless of consumption. It is not an error, and it does not vanish in the months when you use almost nothing; it is the rent for the wire to your house. How the charge is computed and why it exists is covered separately in our fixed charge explainer.
FAC, Duty and the Small Add-On Lines
Between the energy charge and the total sit the lines people understand the least. The fuel adjustment charge — printed as FAC in some states and FPPCA in others — passes through the DISCOM's own fuel costs: coal and gas prices move every quarter, so this line changes even when your usage does not. In quarters when fuel gets cheaper it can even go negative and appear as a credit. The whole mechanism, including why it is on your bill at all, is in our FAC and FPPCA guide.
Electricity duty is a state tax, usually a small percentage of the bill, with exemptions in many states for specific categories. A few states add municipal or grid charges on top. None of these lines are negotiable, but they should be consistent: the duty percentage should match your state's published rate, and a drift is worth a written query. The duty landscape across states is mapped in our duty and surcharges post.
Arrears, Adjustments and the Subsidy Credit
When the current reading settles an earlier estimate, the difference lands as an arrears line — past consumption billed now. This is the line behind most "my bill doubled" panics, and it is usually not an error: the DISCOM under-charged in earlier cycles and is now catching up. In states that run tariff subsidies, a separate credit line reduces the total, and the bill prints both the pre-subsidy and post-subsidy amounts.
If an arrears line appears and you did not expect it, check whether the readings on this bill and the previous one were estimates. Two estimates in a row make a catch-up perfectly normal. If both were actual readings, question the line in writing before paying it under protest — the full list of legitimate reasons a bill rises, in the order to check them, is in why your bill increased.
The Footer: Total, Due Date and Payment
The bottom of the bill carries the only numbers with consequences: the total, the due date, and in most states a second date after which a late payment surcharge starts accruing. Paying after the due date but inside the grace window usually avoids it, though the rule varies by state. The surcharge itself is typically 1.5–2% per month of the overdue amount — a figure that compounds into something serious across a few missed months, as our late payment surcharge post shows with real numbers.
The Five-Minute Audit
Before paying, run this short check. One: the consumer number matches yours. Two: the category and sanctioned load are correct. Three: the units equal the current reading minus the previous reading. Four: units per day is close to your historical average. Five: the duty percentage matches your state's rate. Each check takes under a minute, and each of them has caught a real error on a real bill — the reading box catches the mis-typed digit, the category line catches the wrong tariff, and the units-per-day test catches everything else.
You can also rebuild the whole bill in about two minutes with the bill calculator — enter your units, state and load, and compare the estimate against what the DISCOM printed. If they differ wildly, you know exactly which line to question.
FAQs
Which field on the bill should I check first?
Units per day — billed units divided by the days covered. It is the single number that tells you whether your consumption genuinely changed. Compare it with your average over the last six bills before looking at any rupee figure.
Why does my bill show a previous reading higher than the current one?
The meter rolled over — most household meters reset to zero after a set number of digits, usually after 99,999 units. The billed units are computed with the rollover accounted for, so the numbers remain correct.
What does FPPCA mean on my bill?
It is the fuel and power purchase cost adjustment — the same mechanism as the FAC. Different states use different names for the same fuel-cost pass-through line, which varies with coal and gas prices every billing cycle.
My neighbour pays no duty but my bill shows 16%. Why?
Electricity duty rates and exemptions vary by state and by consumer category — some states exempt small households, agricultural consumers or senior citizens. If your category is right, the difference is simply the state's rules, not an error.
Can I check my slab rates myself?
Yes. Every state regulator publishes its tariff order, and the tariff directory on this site summarises the slab tables per state from the latest orders. Compare your energy line against the slabs to verify the arithmetic.
What is the "E" next to my reading?
It marks an estimated reading — the meter was not physically read that cycle. Pay the bill, but watch the next one: when the true reading is captured, the difference from the estimate is billed as arrears, which is why the follow-on bill often jumps.
