California Natural Gas Supplier Choice, Explained
How the Core Aggregation Transportation program lets eligible Californians choose a gas supplier while the utility keeps delivering.
Updated 2026-10-01 · 6 min read
Two parts of every gas bill
A natural gas bill combines the cost of the gas commodity (supply) with the cost of moving it to you (delivery). Delivery — pipelines, meters, safety — is a regulated utility function. Supply, for eligible core customers, can be purchased from a third party.
What the CAT program is
Core Aggregation Transportation (CAT) is the California framework that allows registered Core Transport Agents to procure gas on behalf of eligible residential and small commercial customers. The utility continues to deliver that gas and generally continues to send the bill.
What to weigh before choosing
Supplier choice is not automatically a savings opportunity. Compare:
- The supplier's per-therm price versus the utility procurement rate
- Fixed or variable pricing
- Contract term and renewal terms
- Monthly fees and early termination fees
- Cancellation and rescission rights