Texas requires most plans to be labeled “Fixed Rate,” but that only fixes the energy rate — not what you pay per kWh once base charges and credits are folded in. We flag a plan “fixed ≠ flat” when the effective price actually swings more than 3.0¢ across 500–2,000 kWh.
Real example. TXU Energy Simple Rate 12, a genuinely steady plan, swings only 2.1¢ (from its base charge alone) — so we do not flag it. But Reliant Power Savings 2,000 kWh 12 swings 8.1¢ because of its credit cliff. Same legal label, wildly different reality.
Interactive chart — open this example in the tool →
“Fixed” tells you the rate won’t change month to month. It says nothing about whether your bill is flat across usage — read the curve.