The companies that deliver natural gas to residential end users are typically called Local Distribution Companies (LDC’s) in the United States, according to the U.S. Energy Information Administration. Some are owned by investors and others are owned by municipalities.
Because of the relatively high cost of creating the network of pipes and other equipment that are used to distribute natural gas to homes, it doesn’t make economic sense for multiple companies to create redundant distribution networks in the same area, leading to “natural monopolies”. According to https://naturalgas.org/naturalgas/distribution/:
Traditionally, local gas utilities have been awarded exclusive rights to distribute natural gas in a specified geographic area, as well as perform services like billing, safety inspection, and providing natural gas hookups for new customers. Like interstate pipelines, utilities have historically been viewed as natural monopolies. Because of the high cost of constructing the distribution infrastructure, it is uneconomic to lay multiple redundant distribution networks in any one area, resulting in only one utility offering distribution services. Because of their position as natural monopolies in a given geographic area, distribution companies have historically been regulated to ensure that monopoly power is not abused, and natural gas consumers do not fall victim to overly high distribution costs or inefficient delivery systems.
Typically a state will have a Public Utilities Commission (PUC), or similar entity, that is in charge of, among other things, providing consumer protection and price regulation for natural gas. According to https://www.ecowatch.com/electricity/public-utilities-commission:
All natural gas companies are subject to PUC approval to operate within state lines and use pipelines, and the PUC must also approve all proposed gas prices before they are charged to consumers.
Another example of the entity in charge of overseeing natural gas delivery prices that LDC’s charge to consumers (or at least exclusive appellate authority for gas utilities not owned by municipalities) is the Railroad Commission (RRC) in Texas. According to https://www.rrc.texas.gov/about-us/faqs/gas-services-faq/texas-natural-gas-rates-faqs/:
Who has jurisdiction over natural gas rates in most Texas municipalities?
The majority of Texas municipalities are served by investor owned utilities. In these municipalities, the municipality grants a franchise to a utility company, and the municipality has original jurisdiction (and the Railroad Commission has exclusive appellate authority) over the rates, operations, and services of the natural gas utility within the municipality. The Railroad Commission has no authority over the rates, operations, and services of a municipally-owned gas utility within the municipality’s boundaries.
The PUC for a state, or the agency filling a similar role such as the RRC in Texas or the New York State Public Service Commission in New York, typically has a process by which an LDC can request an increase in the rate it charges consumers for delivering natural gas. Note that the delivery rate is separate from the natural gas commodity rate. The commodity rate is set by the market and not a regulator, and it is typically passed through directly to the end consumer. The delivery rate is intended to cover all of the costs that the LDC incurs to own, operate, and maintain its system to provide the customer with natural gas, along with a reasonable rate of return for the LDC, as described in https://dps.ny.gov/major-rate-case-process-overview.
Taking New York State as an example, you can find a list of pending rate cases for natural gas rate increases here: https://dps.ny.gov/pending-and-recent-gas-rate-cases. The rate case process in New York State is described in detail here (the same as the final link in the paragraph above): https://dps.ny.gov/major-rate-case-process-overview.
Outside of traditional rate cases, some states have provisions that allow natural gas companies to increase rates on an interim basis to recover the costs of infrastructure investments. For example, a Texas law passed in 2003 called the Gas Reliability Infrastructure Program (GRIP) also allows utilities to request interim rate increases annually for up to six years without going through the full rate review process. Here is an interesting presentation from 2017 from the city of Dallas detailing their review of a rate increase request under this law from Atmos Energy.