The cheapest rates are going to have shorter contract terms. For instance, a 3 month term is cheaper than a 6 month term and a 6 month term is cheaper than a 12-14 month term. So if you are able to remember to call before your contract expires (they will notify via mail you that your contract is about to expire), then the 3 or 6-month term is your best bet. If you don't call to renew/cancel, you will be charged a much higher variable rate on a month-to-month basis. If this is you, sign for a 12-month contract term with the cheapest rate.
CenterPoint Intelligent Energy Solutions LLC, IES, which manages TrueCost, is not the same legal entity as CenterPoint Energy Resources Corp. (CERC) or CenterPoint Energy Houston Electric, LLC (CEHE), nor is IES regulated by the Railroad Commission of Texas or the Public Utility Commission of Texas. You do not have to buy products or services from IES in order to continue to receive quality regulated services from CERC or CEHE.