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All You Need to Know About Texas ESI IDs

If you’re a homeowner, business owner, or renter in Texas, you’ve probably heard of ESI ID numbers, but you might be wondering why having an ESI ID matters and how to find yours.

An Electric Service Identifier (ESI ID) is a unique number created by your local utility based on the location of your property.

Each utility that participates in retail electric choice is responsible for creating, assigning, maintaining, and retiring ESI IDs for its service territory. All utilities follow the same basic format, as required by the Electric Reliability Council of Texas (ERCOT). ESI IDs for a particular location do not change over time and are not reused at multiple locations.

Keep in mind if you have more than one meter, you’ll have an ESI ID for each meter. Although the number is specific to the location of your meter/property, an ESI ID is not the same as a meter number and cannot be found on the meter itself.

What’s the Purpose of an ESI ID?

ESI IDs are used for both residential and commercial properties to set up electricity supply service. These numbers help utility companies easily enroll customers, switch a customer’s service provider, and meter customer energy usage.

ESI IDs are important because they indicate which utility is responsible for delivering electricity to your home. In Texas, your utility might be Oncor, AEP, CenterPoint, or TNMP. Because electricity rates vary by utility, your ESI ID number is necessary to get accurate prices when shopping for an electricity plan.

If you're having trouble picturing what an ESI ID actually looks like, the typical format is 10 XXXXX YYY..YY.

standard ESIID Format

The first two digits of ESI IDs are always 10, followed by a five digit Department of Energy ID Code for the utility, followed by a unique 10 digit number to indicate the premise ID.

How do Utilities Assign ESI IDs?

Each utility has a different way of assigning ESI IDs to its customers. Here’s the breakdown for each:


Oncor’s ESI IDs are 17 digits long, beginning with either 1044372 or 1017699 (for East TX customers), followed by a unique 10-digit code that identifies the premise.

An ESI ID from Oncor will either be 10 44372 00 ######## or 10 17699 00 ######## (East TX customers only).

Oncor ESIID Format

Oncor doesn’t follow any further standardized method for assigning its ESI IDs.

AEP Texas

All ESI IDs assigned for AEP Texas are 17 digits long.

However, AEP Texas Central customers are assigned a code that begins with 10 03278 94, while AEP Texas North customers are assigned a code that begins with 10 20404 97. These codes are followed by a unique eight-digit premise identifier.

An ESI ID from AEP Texas will either be 10 03278 94 ######## or 10 20404 97 ######## (North Texas customers only).


AEP Texas follows no standardized method when assigning the premise code.

Texas-New Mexico Power (TNMP)

ESI IDs assigned by TNMP are 17 digits long and always begin with 10 40051, followed by a ten-digit premise ID number.

An ESI ID from TNMP will be 10 4051 ###### 00 ##.



CenterPoint’s ESI IDs are 22 digits long and begin with 10-08901. The eighth digit will always be “0”.

Digits 9-19 are an 11-digit premise ID number that follows a specific format depending on the customer type.

For most customers, the digits are an internal account number (referred to by CenterPoint as “CIS”). Other formats include BES and SLB account numbers. These acronyms do not have a customer-relevant meaning and instead are just used internally to track and bill usage data.

Digit 20 will either be “1” for metered property or “2” for unmetered property. Digits 21 and 22 will show the last two digits of the year that CenterPoint created the new ESI IDs (or 00 for ESI IDs created before 2001).

An ESI ID from CenterPoint will be 10 08901 0 ########### # ##.

CenterPoint ESIID Format

Finding Your ESI ID

You’ll need your ESI ID to sign up for electricity plans for your home. Our ESI ID lookup tool is an easy way to find your ESI ID, or you can look for it on your electricity bill. Then, you can start shopping for the best rates at WattBuy!

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