Iowa Driver’s License Restriction Codes: Vision, Medical, and CDL

The letter and number codes on an Iowa driver’s license each flag a condition you have to follow whenever you drive. Iowa driver’s license restriction codes cover everything from corrective lenses to ignition interlock devices, adaptive equipment, nighttime driving limits for teens, and commercial vehicle limitations. The code itself is printed on the front of the card; a short explanation appears on the back. Driving in violation of any of them is a simple misdemeanor, and the Iowa Department of Transportation (DOT) can suspend or revoke your license on its own authority if it learns you ignored one.¹

What Each Code Means

The DOT sorts restriction codes into four groups based on your license type.²

Codes That Can Appear on Any Iowa License

B — Corrective lenses required. You must wear glasses or contacts whenever you drive.
C — Mechanical aid required. Specific device (hand controls, steering knob, etc.) listed on the back of the card.
D — Prosthetic aid required. Details on the back of the card.
F — Left and right outside rearview mirrors required on your vehicle.
G — No driving when headlights are required. In practice, no driving from sunset to sunrise or in poor-visibility conditions.
H — Temporary restricted license or work permit.
I — Ignition interlock device required.
J — Additional restrictions printed on the back of the card.
S — Proof of financial responsibility (SR-22 insurance) required.
T — Medical report required at each renewal.
U — Not valid for two-wheel vehicles (motorcycles).
W — Restricted commercial driver’s license.
Y — Intermediate license, with passenger and nighttime limits for drivers under 18.

Noncommercial License Only

8 — Special instruction permit.
9 — Passenger restriction for intermediate license holders.
Q — No interstate or freeway driving.

Commercial Driver’s License Only

E — No manual-transmission commercial motor vehicles.
K — Intrastate driving only.
L — No air-brake-equipped commercial motor vehicles.
M — No Class A passenger vehicles (large buses).
N — No Class A or Class B passenger vehicles.
O — No tractor-trailers.
V — Medical variance document required.

Numbered License Type Codes

A number on the face of the card identifies the license type itself rather than a driving condition:

1 — Motorcycle instruction permit
2 — Noncommercial instruction permit (vehicles under 16,001 lbs. GVWR)
3 — Commercial driver’s instruction permit
4 — Chauffeur’s instruction permit
5 — Motorized bicycle license
6 — Minor’s restricted license
7 — Minor’s school license

How a Code Ends Up on Your License

Most codes are added at the driver’s license station after a vision screening or a driving test. Others come from outside the DOT. Physicians, advanced registered nurse practitioners, physician assistants, and optometrists can report a patient they believe cannot drive safely, and those reports are confidential. Once the DOT gets one, it can require you to submit your own medical report, take a driving test, or both before it will issue or renew your license.³

Law enforcement referrals can also trigger a reevaluation. And the DOT has broad statutory authority to impose whatever restrictions it considers appropriate to match your actual driving ability, including limits on vehicle type, required mechanical controls, and other conditions.¹

Vision Codes and the Thresholds Behind Them

Vision problems are the most common trigger for a restriction, and Iowa ties the codes to specific acuity measurements.

If your visual acuity is 20/40 or better in both eyes (or your better eye) without correction, no restriction is imposed. If you reach 20/40 only with glasses or contacts, you get code B. If your acuity (corrected or not) falls below 20/40 but is at least 20/70, the DOT assigns code G, which bars you from driving when headlights are required. If both conditions apply, both codes appear.⁴

A separate rule addresses drivers with significantly weaker vision in one eye. If your left eye tests worse than 20/100, the DOT assigns code F, requiring left and right outside rearview mirrors. In some cases you can choose between wearing corrective lenses (code B) or installing the mirrors (code F) if lenses bring that eye above 20/100.⁴

You can skip the DOT’s in-house screening by submitting a vision report from a licensed physician or optometrist. The exam has to be within 30 days of your application, and the form must state your measured acuity.⁵

Medical and Adaptive Equipment Codes

Iowa will not issue a license to someone the DOT knows cannot drive safely because of a physical or mental condition, unless that person submits a medical report showing they can. Conditions like paralysis, limb loss, limited mobility, or neurological disorders often produce one or more restriction codes.⁶

Codes C (mechanical aid) and D (prosthetic aid) cover drivers who rely on vehicle modifications or body-worn devices. The specific equipment is spelled out on the back of the license. The DOT typically assigns these codes after a driving test in the modified vehicle, sometimes based on recommendations from an occupational therapist who specializes in driver rehabilitation.

Code T calls for a fresh medical report every time you renew. If you have a history of seizures or episodes of lost consciousness, Iowa requires at least six months free of episodes before you can be licensed, and the DOT will usually start with a six-month medical review before stepping down to a renewal-cycle review.⁶

The medical report itself is not available online. The DOT or your county treasurer’s office provides the form, and a licensed physician fills it out. If you carry a T restriction, the DOT mails you the form about a month before it is due.⁷

What the Y Restriction Requires

A Y on the face of the card means you hold an intermediate license, and there are three extra rules that ride with it beyond any medical or vision codes:

No driving without an adult in the vehicle between 12:30 a.m. and 5:00 a.m. A parent or guardian can waive this for school or work purposes by completing a DOT waiver form that must be kept in the vehicle.
For the first six months, no more than one minor passenger who is not a relative when driving unsupervised. Relatives include siblings, step-siblings, and other minors living in your household.
No use of a cellphone, tablet, or other electronic communication or entertainment device while driving. Permanently installed vehicle equipment is exempt.

⁸

Getting a Restriction Removed

Codes are not permanent. If the underlying condition improves, the DOT will consider lifting the restriction, but you have to bring documentation.

For a vision code, you need a new eye exam showing acuity of 20/40 or better. A vision report signed by a licensed physician or optometrist within the prior 30 days is enough.⁵

For equipment-based codes (C or D), the DOT may ask you to take a driving test in a standard vehicle to confirm you can operate it without the adaptive device. For code T, an updated medical report showing the underlying condition has resolved or stabilized is typically what the DOT wants.

The DOT can also require you to come back for reexamination at a set time and will send a reminder notice when that date approaches. If your restriction was tied to episodes of lost consciousness, plan on being episode-free for at least six months and submitting a favorable medical report before the DOT will remove it.⁶

Penalties for Driving Outside a Restriction

Driving in violation of a restriction printed on your license is a simple misdemeanor in Iowa, treated as a scheduled violation.¹

The fine is only part of it. The DOT can suspend or revoke your license on its own if it receives satisfactory evidence you violated a restriction, and no court conviction is required. An officer who pulls you over and finds you driving at night with a G code, or operating without required adaptive equipment, can cite you on the spot while the DOT acts administratively.⁹

If a violation contributes to a crash, insurance companies routinely review license restrictions afterward, and operating outside your authorized conditions gives them grounds to dispute coverage.

Your Rights Under Federal Disability Law

Title II of the Americans with Disabilities Act applies to every state motor vehicle agency, Iowa’s included. A public entity cannot deny you the opportunity to participate in a government program because of disability, and it cannot use criteria or methods that have the effect of discriminating against people with disabilities.¹⁰

Iowa cannot impose a blanket ban on licensing someone based on a diagnosis alone. Every restriction decision has to rest on an individualized assessment of your actual driving ability, and the DOT is required to provide testing accommodations if you need them. If you believe a code was imposed based on your diagnosis rather than what you can actually do behind the wheel, you can challenge it under federal law.

1
Justia. Iowa Code 321.193 – Restrictions on Licenses, Penalty
2
Cornell Law Institute. Iowa Administrative Code 761-605.8 – Restrictions
3
Justia. Iowa Code 321.186 – Examination of New or Incompetent Operators
4
Iowa Legislature. Iowa Administrative Code 761-604.6 – Visual Acuity Standards
5
Iowa Legislature. Iowa Code 321.186A – Vision Report in Lieu of Vision Test
6
Iowa Legislature. Iowa Administrative Code 761 – Chapter 605, License Issuance
7
Iowa Department of Transportation. Medical Conditions and Driving
8
Iowa Department of Transportation. Intermediate License
9
Iowa Legislature. Iowa Code 321.193 – Restrictions on Licenses, Penalty
10
eCFR. 28 CFR 35.130 – General Prohibitions Against Discrimination