What telescopic actually means
A telescopic tariff prices consumption in layers. The slab table defines bands of monthly units, each with its own rate, and your consumption is cut into pieces that fill those bands in order. Each piece is billed at the rate of the band it lands in.
The name comes from the way the bands nest inside each other like the sections of a collapsing telescope: reaching a higher band does not replace the lower ones, it extends past them. Every consumer pays the cheapest rate on their first units, and only heavy users ever reach the expensive bands at all.
The rule in one line
A higher slab rate applies only to the units above that slab’s lower boundary — never to the units you have already been billed for at cheaper rates.
Telescopic versus non-telescopic billing
The alternative approach — non-telescopic, sometimes called slab-based-on-total billing — looks at your total consumption, picks the single rate for the band it falls in, and applies that rate to every unit. The difference is dramatic. Take 240 units of domestic consumption under the FY 2026-27 rates.
| Method | How it prices 240 units | Energy charge |
|---|---|---|
| Telescopic (actual) | 30 units at ₹1.90, 45 at ₹3.00, 50 at ₹4.50, 100 at ₹6.00, 15 at ₹8.75 | ₹1,148.25 |
| Non-telescopic (hypothetical) | All 240 units at the ₹8.75 band rate | ₹2,100.00 |
Illustrative comparison. Domestic LT supply in the schedule used by this site is telescopic.
Nearly ₹1,000 a month separates the two methods for the same electricity. This is also why third-party "AP electricity rate" posts that simply multiply your units by a single slab rate produce numbers so far above your real bill.
A third structure is the genuinely flat tariff, where a category has one rate for all units and no bands at all. Several categories work this way — LT industry up to 15 kW at ₹6.70 per unit, EV charging stations at ₹6.70, cottage industries at ₹3.75. For these, consumption and cost move in a straight line and there is nothing to optimise around thresholds.
Your average rate is the number that matters
Because of the layering, the useful figure is not your top band rate but your effective average: total bill divided by units consumed. It tells you what an additional or avoided unit is roughly worth to you, and it is the only fair way to compare your costs with someone else’s.
| Monthly units | Energy charge | Average per unit |
|---|---|---|
| 50 units | ₹117.00 | ₹2.34 |
| 100 units | ₹304.50 | ₹3.05 |
| 200 units | ₹867.00 | ₹4.34 |
| 240 units | ₹1,148.25 | ₹4.78 |
| 400 units | ₹2,548.25 | ₹6.37 |
Energy charge only, excluding fixed and customer charges, using FY 2026-27 domestic rates.
Notice how gently the average climbs even as the marginal rate quadruples. A household at 400 units is paying an average of about ₹6.37 per unit while its last units cost ₹8.75. The marginal rate is what you save by cutting consumption; the average is what you are paying overall. Confusing the two leads to bad decisions in both directions.
How much a slab boundary really matters
Since only the units above a boundary are repriced, crossing one is not the disaster it is sometimes made out to be. Ten units past the 400-unit mark cost ₹97.50 instead of ₹87.50 — an extra ₹10.
But the marginal rate itself is worth attention. Once you are consistently in the 226–400 band, every unit you avoid saves ₹8.75, which is more than four times what a unit saves a household sitting in the 31–75 band. Efficiency measures that would never pay back for a low user can pay back quickly for a high one. This is the practical takeaway: know your band, and let it tell you how hard to work at saving.
Where the structure changes
Telescopic slabs are not the whole tariff, and several things sit outside them.
- Fixed charges are driven by your sanctioned load in kW, not by units, so they do not change when you consume less.
- Customer charges are a single flat step chosen by your total monthly consumption, not sliced across bands.
- Flat-rate categories such as LT industry up to 15 kW, EV charging and cottage industry have no bands at all.
- Time-of-day categories vary the rate by the hour of consumption rather than by cumulative units, so when you use power matters more than how much.
- Agricultural categories with a free entitlement work on an annual quota per HP, with only the excess billed.
- Minimum monthly charges can override the calculated total for some commercial and institutional services.
Multi-month and part-month periods
Slab thresholds are written per month. When a billing period covers substantially more or less than a month — a delayed reading, a new connection energised mid-cycle, a spell of provisional billing — the thresholds have to be scaled to the period rather than applied as if it were a single month. If they were not, a two-month reading would artificially push a modest consumer into expensive bands. If a bill covering an unusual period looks wrong, check the reading dates first and raise it with your DISCOM rather than assuming the slab rates changed.
Frequently asked questions
If I cross into a higher slab, is my whole bill recalculated at the higher rate?
No. Under a telescopic tariff only the units above the boundary are billed at the higher rate. Everything below it stays priced at the lower band rates.
Why is my average rate lower than every rate in the table except the first?
Because your consumption is spread across the bands. A large share of your units are billed in the cheaper lower bands, which pulls the average down well below your highest band rate.
Are commercial tariffs telescopic too?
The commercial LT slabs in the FY 2026-27 schedule used here are applied telescopically, starting at ₹5.40 per unit and rising to ₹9.95. The bands are wider and start higher than domestic ones, and a minimum monthly charge may apply.