Work out the energy charge for your two-month units slab by slab, using the Commission-determined LT-IA domestic rates in TNERC Suo-motu Order No. 6 of 2025, before the Tamil Nadu government subsidy.
What it calculates. Enter the units on your TNPDCL bill for the two-month cycle. The calculator charges each block of units at its own rate (telescopic billing): the first 400 units at ₹4.95, units 401–500 at ₹6.65, 501–600 at ₹8.80, 601–800 at ₹9.95, 801–1,000 at ₹11.05 and every unit above 1,000 at ₹12.15. These are the Commission-determined LT-IA domestic energy charges in TNERC Suo-motu Order No. 6 of 2025 dated 30 June 2025, effective 1 July 2025. The LT-IA fixed charge is nil. The order sets one slab table for all domestic consumption, so a household above 500 units still pays the lower rates on its first 500 units; only the units above each limit pay the higher rate.
Worked examples. 500 units: 400 × ₹4.95 + 100 × ₹6.65 = ₹2,645, an average of ₹5.29 a unit. 800 units: ₹1,980 + ₹665 + ₹880 + 200 × ₹9.95 = ₹5,515, an average of about ₹6.89 a unit.
What you actually pay is lower. The order says this tariff is "to be partly subsidised by the Government", and the Government of Tamil Nadu agreed to absorb the July 2025 increase for domestic consumers. Your bill shows the government subsidy as a separate line, including the free units. From 10 May 2026, according to reports of G.O. (Ms) No. 50 and the TNERC subsidy order that followed, households using up to 500 units in two months get 200 units free, and those above 500 units get 100 units free. Read the payable amount from your own bill.
Check the rates are current. The order provides for a CPI-linked revision from 1 July 2026. On 27 October 2026 TNPDCL's tariff page still listed only the 2025 order, so check it before relying on these figures. The calculator does not cover Delhi or other states, which bill monthly with their own slabs and fixed charges; their worked examples are in the guides.
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