New Hampshire DWI Laws: BAC Limits, Penalties, and License Loss

A first DWI conviction in New Hampshire carries a minimum $500 fine, a license revocation of at least nine months, mandatory substance abuse screening, and a required impaired driver education program before you can drive again. New Hampshire DWI penalties climb from there based on your blood alcohol level, prior convictions, whether anyone was hurt, and whether a child was in the car. The most serious cases reach felony territory, with mandatory jail and years of lost driving privileges.

First Offense Penalties

A first DWI under RSA 265-A:2 is a class B misdemeanor. The court must impose a fine of at least $500, plus penalty assessments that push the real total higher. Your license is revoked for a minimum of nine months, and a judge can extend that to two years.¹

The fine and revocation are only part of the sentence. Within 14 days of conviction, you have to complete an alcohol and drug abuse screening. If the screening points to a substance use disorder, a full evaluation follows within 30 days, along with whatever treatment plan comes out of it. A state-approved impaired driver education program and a victim impact panel are also required before the DMV will consider restoring your license.¹

Drivers under 21 face the same fines and program obligations, but their minimum license loss is one year rather than nine months. The underage BAC threshold is 0.02 percent, far below the 0.08 limit that applies to adult drivers.²

You can also be charged without ever registering 0.08. The statute covers impairment from controlled drugs, prescriptions, over-the-counter medications, or any combination. Officer observations like swerving, slurred speech, and failed field sobriety tests can support a conviction on their own.²

When a DWI Becomes Aggravated

Certain facts automatically upgrade a standard DWI to Aggravated DWI under RSA 265-A:3. Any one of these is enough:³

Driving 30 mph or more over the posted limit while impaired.
A BAC of 0.16 percent or higher, double the legal limit.
Causing a crash that results in serious bodily injury.
Trying to flee or elude a law enforcement officer.
Having a passenger under 16 in the vehicle.

Most aggravated DWI convictions are class A misdemeanors. The minimum fine jumps to $750, the license revocation runs at least 18 months, and the court must impose a 17-day jail sentence with 12 days suspended, leaving a mandatory five days in a county correctional facility. An ignition interlock device is required once your revocation ends.¹

Aggravated DWI Causing Serious Bodily Injury

If the aggravated DWI involves a crash that seriously injures someone, the charge becomes a class B felony. The minimum fine is $1,000, and the mandatory jail term rises to 35 consecutive days with 21 suspended, meaning at least 14 days behind bars. A felony conviction also carries collateral consequences including loss of firearm rights and a permanent felony record.¹

Repeat Offenses and the 10-Year Lookback

New Hampshire uses a 10-year lookback period. Any prior DWI or aggravated DWI conviction within the 10 years before your new offense will elevate the charge. A second DWI in that window is a class A misdemeanor with a minimum $750 fine, significantly more mandatory jail time than a first offense, and a license revocation that often reaches three years or more.¹

A third DWI within the window remains a class A misdemeanor but carries longer mandatory jail and extended revocation. Out-of-state convictions count. A prior DWI from Vermont or Massachusetts will be treated as a prior for New Hampshire’s repeat-offense rules.

DWI Causing Death

When an impaired driver kills someone, the charge moves out of the DWI statutes entirely. Prosecutors file negligent homicide under RSA 630:3, a class A felony carrying a maximum sentence of 7.5 to 15 years in state prison.⁴

The court must revoke your license indefinitely, with no eligibility to even petition for reinstatement for at least seven years. If alcohol was involved, an ignition interlock requirement of up to five years can be imposed after any eventual reinstatement.⁴

The Administrative License Suspension

The DMV runs its own civil suspension process that operates independently of the criminal case, and it catches many people off guard. Under RSA 265-A:30, two things trigger an administrative suspension: failing a chemical test or refusing one.

Fail a breath or blood test with a BAC of 0.08 or higher (0.02 if you are under 21) and the DMV will suspend your license for six months on a first offense. Any prior DWI conviction, prior refusal, or prior administrative suspension pushes that suspension to two years.⁵

The suspension does not take effect right away. After the officer serves notice, you get a 30-day temporary license. Within that window you can request an administrative hearing to challenge the suspension; miss the deadline and the suspension kicks in automatically. The hearing is narrow, limited to whether the officer had legal grounds to stop you and whether you actually failed or refused the test. Whatever the DMV imposes stacks on top of any criminal court penalties.⁵

Refusing the Breath Test

By driving on New Hampshire roads, you have already consented to chemical testing if arrested on suspicion of DWI. That is what the implied consent law in RSA 265-A:4 means in practice.⁶

You can still refuse. A first refusal brings a 180-day administrative suspension; a second refusal brings two years. Refusing does not block the DWI prosecution itself. Officer observations, field sobriety results, and other evidence can still support a conviction.

Getting Your License Back

Serving out your revocation period is not enough on its own. The DMV requires several completed steps before it will reinstate you.

Impaired Driver Care Management Program

Every DWI offender has to participate in a state-approved Impaired Driver Care Management Program, which includes screening, education, and a clinical evaluation to determine whether ongoing treatment is needed. Repeat offenders face more intensive requirements and may need to complete extended treatment before driving privileges can be restored.⁷

Ignition Interlock Device

For aggravated and repeat offenses, the court will order an ignition interlock device on any vehicle you own or drive. You blow into a sensor before the engine starts, and the device requests additional samples while you drive. The requirement runs 12 months to two years after your revocation period ends.⁸

Even when the court does not order an interlock, the Commissioner of Safety has independent authority to require one as a condition of reinstating any license in a case involving alcohol.⁹

You pay for the device yourself. Monthly lease fees typically start around $55, calibration appointments every one to three months run roughly $20 each, installation is a separate one-time charge, and failed tests or tampering can trigger lockout fees around $75. Expect $800 to $1,500 over a 12-month interlock period.

SR-22 Insurance

You will need to file an SR-22 certificate of financial responsibility after a DWI. It is not a separate policy but a form your insurer files with the DMV confirming you carry at least the minimum required coverage. SR-22 filing generally has to stay in place for three years after a first DWI. Any lapse triggers an immediate re-suspension, and the clock restarts.

Reinstatement Fee

Once your revocation period has ended and your program requirements are complete, you pay a $100 restoration fee to the DMV before your license is reactivated. CDL holders also pay $100 for commercial driving privilege restoration.¹⁰

What a DWI Does to a CDL

Commercial drivers face a second layer of consequences under federal law. The federal BAC threshold for a commercial vehicle operator is 0.04 percent, half the standard limit.¹¹

Under 49 CFR 383.51, a first DWI-related conviction disqualifies you from operating any commercial vehicle for one full year. That applies even if you were driving your personal car when arrested. A second conviction for any major offense, including DWI, results in a lifetime CDL disqualification. States may allow reinstatement after 10 years if you complete a rehabilitation program, but a third conviction after reinstatement makes the disqualification permanent. Refusing a chemical test counts as a major offense under these rules, so the CDL consequences of refusing match those of a conviction.¹²

Travel After a DWI

Canada classifies impaired driving as “serious criminality,” and a single DWI conviction can make you inadmissible at the border, even years after the fact. Entering generally requires a Temporary Resident Permit (processing fee C$200), qualifying as “deemed rehabilitated,” or formally applying for criminal rehabilitation.¹³

A DWI can also cost you Global Entry or TSA PreCheck. The background check for trusted traveler programs covers criminal history, and a DWI conviction can lead to denial or revocation. Reconsideration requires court disposition documents for every arrest and conviction.¹⁴

What a First Offense Actually Costs

The court fine is a small share of the real bill. A typical first-offense breakdown looks like this:

Court fine and penalty assessments: $500 minimum fine, with surcharges pushing the total to $620 or more.
Defense attorney: flat fees for a first offense generally run $1,500 to $5,000.
Impaired driver education program: typically several hundred dollars.
Substance abuse screening and any resulting evaluation or treatment.
SR-22 insurance: the filing itself is minor, but the rate increase behind it often adds $1,000 or more per year for three years.
License reinstatement fee: $100.¹⁰
Victim impact panel fee, which varies by provider.

Add $800 to $1,500 for an ignition interlock on aggravated or repeat offenses. Attorney fees for repeat or felony cases often start at $5,000 and can exceed $10,000. All in, even a straightforward first-offense DWI usually runs $5,000 to $10,000 out of pocket, and aggravated or repeat offenses can easily double that before counting lost wages from jail time or the months you cannot drive.

1
New Hampshire General Court. New Hampshire Code 265-A:18 – Penalties for Intoxication or Under Influence of Drugs Offenses
2
New Hampshire General Court. New Hampshire Code 265-A:2 – Driving or Operating Under Influence of Drugs or Liquor; Driving or Operating With Excess Alcohol Concentration
3
New Hampshire General Court. New Hampshire Code 265-A:3 – Aggravated Driving While Intoxicated
4
New Hampshire General Court. New Hampshire Code 630:3 – Negligent Homicide
5
New Hampshire General Court. New Hampshire Code 265-A:30 – Administrative License Suspension
6
New Hampshire General Court. New Hampshire Code 265-A:4 – Implied Consent of Driver or Operator
7
NH Division of Motor Vehicles. Impaired Driver Intervention Programs
8
New Hampshire General Court. New Hampshire Code 265-A:36 – Alcohol Ignition Interlock Program Established
9
New Hampshire General Court. New Hampshire Code 265-A:36-a – Enhanced Technology Ignition Interlock Device
10
NH Division of Motor Vehicles. Suspension and Restoration
11
Federal Motor Carrier Safety Administration. Is a Driver Disqualified for Driving a CMV While Off-Duty With a Blood Alcohol Concentration Over 0.04 Percent?
12
eCFR. 49 CFR 383.51 – Disqualification of Drivers
13
Canada Border Services Agency. Find Out if You Can Enter Canada: Inadmissibility
14
U.S. Customs and Border Protection. Trusted Traveler Program Denials