Why your bill changes even on a fixed-rate plan

The overwhelming reason a bill changes is that you used a different amount of electricity. Air conditioning is the largest single load in most Texas homes, and the difference between a mild April and a hot August is easily a factor of two or three.

Billing periods also vary in length. A 33-day cycle costs more than a 28-day cycle at exactly the same daily usage, and the two can fall consecutively.

Roughly a third of a typical Texas bill is delivery — the utility that owns the poles and wires at your address. Those charges are set by the utility and approved by the regulator, and they change on their own schedule regardless of your contract.

Most fixed-rate plans pass those changes straight through, and the terms of service say so. So a fixed-rate customer can genuinely see their per-kilowatt-hour cost move without their retailer having done anything at all.

A base charge is the same every month, so it makes a small bill look expensive per kilowatt-hour and a large one look cheap. A minimum-usage fee appears only in months you fall below a threshold — which is exactly the months your bill was already low, making the swing look worse than it is.

If your bill jumped in a month you know you used less power, this is the first thing to check on your Electricity Facts Label.

Your energy rate itself changing mid-contract. On a genuine fixed-rate plan that should only occur through the pass-through provisions the label discloses.

If your rate moved for another reason, the first thing to check is whether your contract expired. A term that ends without action typically rolls onto a month-to-month variable product at a much higher price, and the bill that arrives afterwards is the most common version of this complaint.