California offers a few FasTrak transponder types, and the right one depends on two questions: do you ever drive express lanes, and do you ever carry passengers who would qualify you for a carpool discount? Most drivers need either the Standard tag (full toll every time) or the Flex tag (a switch you set for occupancy). Motorcycles and vehicles with metallic windshields use sticker versions instead, and drivers who only cross bridges can skip the transponder entirely with a License Plate Account.
The Standard Transponder
The Standard tag comes in two forms. One is a thin sticker that adheres to the windshield. The other is a hard-case device with adhesive strips that mounts near the rearview mirror; it contains a battery and may beep when roadside equipment reads it.1The Toll Roads. Types of FasTrak Transponders Both transmit your account information to overhead sensors and debit the toll from your prepaid balance.
The Standard tag has no way to tell the system how many people are in your vehicle. You pay the full posted toll every time, even with a full car. On Bay Area toll bridges that doesn’t matter, since the toll is flat. On express lanes it does: you miss every carpool discount you would otherwise qualify for.2FasTrak. Carpooling Guide
Get the Standard tag if your driving is limited to state-owned bridges, or if you only ever drive express lanes solo. The hard-case version is portable between vehicles because you can peel it off one windshield and reattach it to another.3FasTrak. FasTrak Throughout California
The FasTrak Flex Transponder
The Flex is a hard-case tag with a three-position sliding switch on its face. Before you drive, you set it to 1 for solo, 2 for two occupants, or 3+ for three or more. Overhead equipment reads that setting along with your account data and applies the correct rate.3FasTrak. FasTrak Throughout California
On toll bridges the Flex works exactly like a Standard tag regardless of switch position. Its value shows up on express lanes, where carpools qualify for reduced or free tolls. If you drive express lanes with passengers even occasionally, the Flex is the only transponder that unlocks those savings.2FasTrak. Carpooling Guide
Set the switch honestly. If enforcement cameras detect a mismatch between the position you selected and the actual number of people in your vehicle, you can receive a toll evasion notice. A first notice adds a $10 penalty on top of the unpaid toll, and a second notice raises the penalty to $30.4C/CAG. Schedule of Penalties for Toll Evasion Violations
Specialty Sticker Transponders
Two additional form factors cover vehicles that can’t use a normal windshield tag.
- The headlamp sticker transponder is for vehicles whose windshields contain a metallic coating that blocks the signal. It adheres to the headlamp lens.
- The motorcycle sticker transponder mounts on a motorcycle’s headlamp lens or cover, since motorcycles have no windshield.
Both specialty stickers function like a Standard tag and cannot communicate occupancy. Motorcycles are treated as carpools on most express lanes, though, and ride toll-free when the rider has a Flex tag set to the appropriate position.1The Toll Roads. Types of FasTrak Transponders
License Plate Accounts: Skipping the Transponder
If you only cross Bay Area toll bridges and never use express lanes, you can open a License Plate Account instead of ordering a tag. Your plate is linked to your FasTrak account and bridge cameras read it as you pass. Two versions exist: a long-term account for regular commuters and a short-term account that covers tolls within a 48-hour window or up to 30 days in advance.5FasTrak. License Plate Account
The tradeoff is significant. License Plate Accounts cannot be used on express lanes and do not qualify for carpool discounts on bridges. If you need either, you need a physical transponder.
What Happened to the CAV Transponder
California previously offered a FasTrak CAV (Clean Air Vehicle) transponder that let drivers with a DMV-issued CAV decal access carpool lanes and reduced express lane tolls while driving solo. That program has ended. The DMV stopped accepting new CAV decal applications on August 29, 2025, and all existing decals became invalid on October 1, 2025. Clean air vehicles now meet the same occupancy requirements as any other car.6California Department of Motor Vehicles. Clean Air Vehicle Decals
If you already have a CAV transponder, you don’t need to order a replacement. FasTrak automatically converted every CAV tag into a standard Flex, so yours now works as a regular Flex with the same three-position switch.7FasTrak. Clean Air Vehicle Discounts Being Discontinued
How Express Lane Occupancy Rules Affect Your Choice
Not all express lanes use the same carpool threshold, and getting this wrong on a Flex switch means paying full price when you qualified for a discount. In the Bay Area, express lanes fall into two tiers:
- Two-person carpool lanes (I-580, I-680): set the Flex to 2 or 3+ and your carpool rides toll-free.
- Three-person carpool lanes (SR-237, I-80, I-880, US-101, US-101/SR-85): three or more occupants ride free with the switch on 3+; two occupants get a 50% discount with the switch on 2; a solo driver on position 1 pays the full dynamic toll.
A Flex tag set to position 1 or a Standard tag always pays full toll on every express lane, no matter how many people are actually in the car.2FasTrak. Carpooling Guide
Express lanes in Los Angeles, Orange County, San Diego, and the Inland Empire each set their own occupancy thresholds. Before using an unfamiliar corridor, check the operating agency’s website to confirm whether 2+ or 3+ is required for a discount.
What It Costs to Open an Account
Every transponder requires a $25 prepaid starting balance to cover upcoming tolls. FasTrak also charges a $5 refundable security deposit per tag, though the deposit is waived for up to three tags on accounts set up with automatic replenishment. Additional tags beyond three still carry the $5 deposit.8Bay Area FasTrak. Get FasTrak
There is no monthly maintenance fee on transponder accounts. Drivers who use an invoice-based account instead pay a $2 fee per statement.9The Toll Roads. Do FasTrak Accounts Have Account Maintenance Fees?
Ordering the Right Tag
You can order a transponder online through the FasTrak website for your region or in person at a customer service center. Have your name and contact details, your vehicle’s make, model, year, and license plate number, and a credit or debit card ready for the prepaid balance.8Bay Area FasTrak. Get FasTrak Signing up online creates your web account automatically, and FasTrak mails the transponder.10FasTrak. Order Online
Open the account through the agency that operates the facility you use most often. That agency will send you the correct transponder model and match you to the rules for your corridor.11The Toll Roads. FasTrak Throughout California When the tag arrives, mount it near the rearview mirror so the overhead sensors have a clear read. If you chose a Flex, check the switch position before every trip.