If you live in Tamil Nadu and receive an electricity bill from TANGEDCO, you have probably noticed that your bill does not simply multiply your total units by a single rate. Instead, it applies different rates to different ranges of consumption – this is the slab-based tariff system.
This guide gives you a complete, plain-language explanation of how the TANGEDCO electricity tariff works for domestic consumers in 2024 – 2025 – including the current slab rates, why the system causes bill shock, and how to calculate your own bill step by step.
Try it yourself: Use our TNEB Bill Calculator to instantly calculate your bill using these exact tariff slabs. Enter your units and see the full slab-wise breakdown.
What Is the TANGEDCO Domestic Tariff?
TANGEDCO (Tamil Nadu Generation and Distribution Corporation) is the body responsible for electricity distribution in Tamil Nadu. The domestic tariff applies to all households under the LT-IA (Low Tension – Domestic)consumer category – which covers the vast majority of residential electricity connections in the state.
The tariff is structured as a slab-based, telescopic pricing system. This means different unit ranges are charged at different rates, and crossing certain consumption thresholds changes the rates applied across all slabs – not just the units above the threshold.
Current Domestic Tariff Slabs (Effective July 2024)
The following tariff rates were revised by TANGEDCO effective July 2024 and are currently in force:
| Units Consumed (Bi-monthly) | Rate Per Unit | Notes |
|---|---|---|
| 0 – 100 units | ₹0 (Free) | 100% Government subsidy for all domestic consumers |
| 101 – 200 units | ₹2.35 per unit | Only if total consumption ≤ 500 units |
| 201 – 400 units | ₹4.70 per unit | Only if total consumption ≤ 500 units |
| 401 – 500 units | ₹6.30 per unit | Approaching telescopic threshold |
| 501 – 600 units | ₹8.40 per unit | Telescopic repricing applies from this point |
| 601 – 800 units | ₹9.45 per unit | Higher tariff continues |
| 801 – 1000 units | ₹10.50 per unit | Significant bill amount expected |
| Above 1000 units | ₹11.55 per unit | Highest domestic slab rate |
What Is the Telescopic Tariff System?
The term “telescopic” refers to how the tariff structure collapses or expands depending on total consumption. In Tamil Nadu’s system, when your bi-monthly consumption exceeds 500 units, the lower slab rates that applied below 500 units are no longer valid — and higher rates are applied across the entire consumption, not just the units above 500.
This is the root cause of the sharp bill jumps that many Tamil Nadu consumers experience when they cross the 500-unit mark. The system is designed to incentivise lower consumption while ensuring higher consumers pay progressively more.
Fixed Charges for Domestic Consumers
In addition to energy charges, TANGEDCO levies a fixed charge based on your connected load, regardless of how many units you consume:
| Connected Load | Fixed Charge (per 2 months) |
|---|---|
| Up to 500 watts | ₹30 |
| 501W – 1 kW | ₹45 |
| Above 1 kW | ₹45 + ₹30 per additional kW |
Free Electricity Subsidy: How It Works
The Tamil Nadu government provides 100 units of free electricity per billing cycle to all domestic consumers. Here is exactly how it applies:
- If you consume up to 100 units – your entire bill is ₹0 (no energy charge at all).
- If you consume more than 100 units – the first 100 units are free, and charges begin from the 101st unit.
- The subsidy applies automatically – you do not need to apply for it separately.
- When consumption crosses 500 units, the subsidy benefit on lower slabs may be effectively reduced due to telescopic repricing.
Strategy: If you live alone or in a small household, keeping your consumption under 100 units makes your bill ₹0. For larger families, tracking your usage and staying under 500 units bi-monthly is the most impactful way to reduce your bill.
How Often Are Tariff Rates Revised?
TANGEDCO revises tariff rates periodically, typically following a petition to the Tamil Nadu Electricity Regulatory Commission (TNERC). The last major revision was in July 2024. Before that, tariffs had been revised in 2020 and 2017.
When a new tariff is announced, it typically takes effect from the next billing cycle after the announced date. TANGEDCO publishes tariff orders on the TNERC website and issues press releases for each revision.
Frequently Asked Questions
Why does my bill double when I cross 500 units?
Because TANGEDCO uses a telescopic tariff. When consumption crosses 500 units, the rates for the lower slabs (101–500 units) are repriced at higher rates – not just the units above 500. This restructuring causes a disproportionate jump in the total bill.
Is the 100-unit free electricity available to all domestic consumers?
Yes. The Tamil Nadu government’s free electricity subsidy of 100 units per billing cycle applies automatically to all domestic (LT-IA) consumers. If your consumption is 100 units or below, your energy charge is zero. No separate application is needed.
Do commercial connections use the same tariff?
No. Commercial connections fall under LT-II and have different tariff rates and slab structures. The rates described in this article apply only to domestic (LT-IA) consumers. Agriculture and industrial connections have their own separate tariff schedules.
When was the last tariff revision by TANGEDCO?
The most recent tariff revision took effect in July 2024. This was approved by the Tamil Nadu Electricity Regulatory Commission (TNERC). The rates listed in this article reflect this latest revision.