TNEB Bill for 400 Units: How Much Will You Pay in Tamil Nadu?
Direct Answer:
A TNEB electricity bill for exactly 400 units in Tamil Nadu costs ₹940.00. Under the active domestic (LT Tariff 1A) schedule, the first 200 units are completely free (₹0.00), and the remaining 200 units (units 201 to 400) are billed at ₹4.70 per unit (200 × ₹4.70 = ₹940.00). With zero fixed charges and no electricity duty on residential connections, your total bi-monthly payable amount is ₹940.
How TNPDCL Calculates the 400-Unit Bill
Residential consumers in Tamil Nadu are billed once every two months (a 60-day bi-monthly cycle). When total bi-monthly consumption remains at or below 500 units, TNPDCL applies the consumer-friendly subsidized tariff structure published by the Tamil Nadu Electricity Regulatory Commission (TNERC):
- First 200 units (0 to 200): Free of charge (₹0.00).
- Next 200 units (201 to 400): ₹4.70 per unit.
- Units 401 to 500: ₹6.30 per unit (applicable only if consumption exceeds 400 units).
- Fixed charges & regulatory duty: ₹0 for residential consumers.
At exactly 400 units, you exhaust the first paid slab without entering the higher ₹6.30 slab. This yields an effective overall rate of just ₹2.35 per unit across your entire 400 units of consumption.
Slab breakdown for 400 Units (Bi-Monthly)
This breakdown is programmatically generated from the live calculation engine modeled on published tariff schedules:
| Slab Range | Units Billed | Rate per Unit (₹) | Energy Charge (₹) |
|---|---|---|---|
| 0 – 200 units (Subsidized Allowance) | 200 | ₹0.00 | ₹0.00 |
| 201 – 400 units | 200 | ₹4.70 | ₹940.00 |
| Fixed Charges (LT-1A Domestic) | — | — | ₹0.00 |
| Electricity Duty | — | — | ₹0.00 |
| Net Payable Amount | — | ₹940.00 |
Comparing 350, 400, and 450 Units: Straddling the Slab Boundary
The 400-unit mark sits right at the boundary between Slab 2 (₹4.70/unit) and Slab 3 (₹6.30/unit). If your household usage drifts slightly above 400 units, how much more do you pay? Here is the estimated side-by-side comparison:
| Total Bi-Monthly Units | 0–200 Units (₹0) | 201–400 Units (₹4.70) | 401–500 Units (₹6.30) | Total Bi-Monthly Bill | Effective Rate/Unit |
|---|---|---|---|---|---|
| 350 units | 200 units (₹0) | 150 units (₹705.00) | 0 units | ₹705 | ₹2.01 |
| 400 units | 200 units (₹0) | 200 units (₹940.00) | 0 units | ₹940 | ₹2.35 |
| 450 units | 200 units (₹0) | 200 units (₹940.00) | 50 units (₹315.00) | ₹1255 | ₹2.79 |
Notice that crossing 400 units to reach 450 units adds 50 units @ ₹6.30 = ₹315. Your previous 200 free units and ₹940 for the 201–400 slab remain completely intact.
Is 400 Units a "Subsidy Cliff"? (399 vs 401 Units Explained)
Consumers often worry that crossing 400 units will trigger a penalty. In reality, the transition from 399 to 401 units is completely continuous (telescopic):
The total difference is just ₹11.00. You only pay ₹6.30 for the single unit that crossed 400. The true "cliff" occurs only when total consumption exceeds 500 units, where 100 free units are revoked entirely.
Check Other Consumption Brackets
Explore estimated calculations for lower usage brackets or check your risk of crossing the 500-unit subsidy threshold: