Colorado's toll system charges you per trip, not through registration
Colorado has three toll roads: I-25 between Castle Rock and the New Mexico border, US 36 between Boulder and I-25, and I-270 connecting I-25 to I-76. You don't pay tolls through your vehicle registration. Instead, you pay each time you use a toll road, either with a transponder account or by license plate invoice.
The tolls fund maintenance and expansion of these specific highways. Rates vary by time of day and direction of travel — peak hours cost more than off-peak hours. If you drive a toll road without a transponder or valid payment method, the Colorado Department of Transportation (CDOT) will mail you an invoice based on your license plate.
Key Takeaways
- Colorado toll roads charge per trip using either a transponder account or license plate invoicing, not through registration fees.
- I-25, US 36, and I-270 are the only toll roads in Colorado, and rates change by time of day and traffic direction.
- You can set up a transponder account online through CDOT's toll website to avoid license plate invoices and receive a small discount.
- If you receive a toll invoice in the mail, you have 30 days to pay or dispute the charge through CDOT.
- Unpaid toll debt can prevent your vehicle registration from renewing until the debt is resolved.
Setting up a transponder account to avoid invoices
A transponder is a small electronic device you mount on your windshield that automatically deducts toll charges from a prepaid account. Setting one up takes about 10 minutes on CDOT's toll website. You'll need a valid email address, a payment method (credit card or bank account), and your vehicle's license plate number.
Transponder users pay a small discount compared to drivers who receive license plate invoices — typically 10 to 15 percent less per trip. You can add multiple vehicles to one account and monitor charges in real time through your online dashboard. If you lose or damage a transponder, CDOT will mail you a replacement at no charge.
Understanding toll rates and peak pricing
Toll rates on Colorado's three highways change throughout the day. During peak commute hours (typically 6 a.m. to 10 a.m. and 3 p.m. to 7 p.m. on weekdays), rates are highest. Off-peak hours have lower rates. Some sections of I-25 also use reversible lanes that change direction based on traffic flow, and rates differ by direction.
A single trip on I-25 through the Denver metro area might cost $1 to $3 during off-peak hours and $4 to $8 during peak hours, depending on the specific segment and current traffic. US 36 rates follow a similar pattern. CDOT publishes current rates on its toll website, and you can check what a specific trip will cost before you drive.
What happens if you drive without paying
If you use a toll road without a transponder and your license plate isn't registered with a toll account, CDOT will photograph your plate and mail you an invoice within 30 days. The invoice includes the toll charge plus a $5 administrative fee. You have 30 days from the invoice date to pay online, by mail, or by phone.
If you don't pay within 30 days, CDOT can send a second notice with an additional $10 late fee. Unpaid tolls can eventually affect your vehicle registration renewal — the state may place a hold on your registration until the debt is resolved. Disputing a charge is possible if you believe the invoice is incorrect; you can contact CDOT's toll customer service with your invoice number and the reason for the dispute.
Transponder versus license plate invoicing costs
| Payment Method | Setup Time | Per-Trip Discount | Administrative Fees | Best For |
|---|---|---|---|---|
| Transponder Account | 10 minutes online | 10–15% | None | Frequent toll road users |
| License Plate Invoice | None (automatic) | None | $5 per invoice | Occasional users |
If you use a toll road once or twice a year, the license plate invoice method works fine — you'll pay the toll plus $5 and move on. If you commute on I-25 or US 36 regularly, a transponder account saves money quickly. Someone using I-25 daily during peak hours could save $50 to $100 per month with a transponder compared to paying invoices.
The choice between the two methods depends on your driving patterns. Occasional users benefit from the simplicity of automatic invoicing, while regular commuters recoup the setup time within a few weeks of transponder use.
Tolls and your vehicle registration
Unpaid toll debt doesn't directly appear on your registration bill, but it can prevent you from renewing your registration. When you attempt to renew through the Colorado Department of Revenue, the system checks for outstanding toll debt. If you owe more than one unpaid invoice, the state will place a registration hold until you settle the debt with CDOT.
You can check for outstanding toll debt on CDOT's website by entering your license plate number. If you find unpaid invoices, paying them when ready clears the hold and allows your registration renewal to proceed. This check happens automatically during the renewal process, so you won't be surprised at the DMV.
Frequently Asked Questions
Do I have to use a transponder on Colorado toll roads?
No. You can drive without a transponder and pay by license plate invoice instead. However, you'll pay an extra $5 administrative fee per invoice and won't receive the transponder discount on the toll itself. A transponder is optional but saves money if you use toll roads regularly.
Can I use my transponder from another state on Colorado toll roads?
It depends on the transponder. Some regional systems are compatible with Colorado's system, but many are not. Contact CDOT's toll customer service with your transponder type to confirm compatibility. If your out-of-state transponder doesn't work, you'll need to set up a Colorado transponder account or pay by license plate invoice.
What if I dispute a toll charge on my invoice?
Contact CDOT's toll customer service within 30 days of receiving the invoice with your invoice number and the reason for the dispute. Common disputes include duplicate charges or charges for trips you didn't make. CDOT will investigate and either remove the charge or explain why it's valid.
Do toll charges appear on my vehicle registration bill?
No, toll charges don't appear on your registration bill. However, unpaid toll debt can prevent you from renewing your registration. Check CDOT's website for outstanding toll debt before you renew. If you owe tolls, pay them first to clear the registration hold.
Are there toll discounts for low-income drivers?
Colorado does not currently offer income-based toll discounts. However, some commercial vehicles and motorcycles have different rate structures. Check CDOT's toll website to see if your vehicle type qualifies for a different rate.