New Hampshire DWI Laws

Last reviewed July 2026 · 8 primary sources · How we research and review these pages

Reviewed by the LegalLimit editorial team →

Standard BAC limit

0.08%

Enhanced BAC threshold

0.16%

Commercial driver BAC

0.04%

Under-21 BAC

0.02%

Prior-offense lookback

10-year window

Aggravating factors

High BAC (≥ 0.16) — aggravated DWI: Under RSA 265-A:3, III, a BAC of 0.16 or above is itself aggravated DWI. An aggravated DWI carries a mandatory 17-day sentence (5 served), $750+ fine, 18-month revocation, and mandatory IID (§ 265-A:18, I(b)).
Aggravated DWI causing serious bodily injury (class B felony): Under RSA 265-A:3, I(b)/II(b), a DWI that causes a collision resulting in serious bodily injury is aggravated DWI, sentenced under § 265-A:18, I(c) as a class B felony: $1,000+ fine, 35 days (14 served), 18-month revocation, mandatory IID.
Passenger under 16 (aggravated DWI + max-revocation): Under RSA 265-A:3, I(d)/II(d), transporting a passenger under 16 makes the offense aggravated DWI. Under § 265-A:18, VIII, a conviction transporting a person under 16 requires the MAXIMUM revocation period for the section violated and bars restoration until IDCMP screening, evaluation, and the impaired-driver education program are complete.
DUI causing death — negligent homicide (class A felony): Under RSA 630:3, II, causing the death of another while operating under the influence of intoxicating liquor or a controlled drug is negligent homicide, a class A felony. The court SHALL revoke the license indefinitely (not restorable for ≥7 years) and MAY require up to 5 years of IID as a restoration condition (RSA 630:3, III).
Other aggravated-DWI triggers (+30 mph, eluding, CMV ≥10,001 lbs, divided-ways violation): Under RSA 265-A:3, I/II(a)/(c)/(e), DWI is aggravated if the driver also sped more than 30 mph over the limit, attempted to elude an officer, or drove a vehicle with a gross combination weight rating of 10,001+ pounds. Each carries the class A misdemeanor aggravated-DWI penalty (§ 265-A:18, I(b)). Effective January 1, 2026 (Laws 2025, ch. 290), a sixth trigger (§ 265-A:3, I/II(f)) makes DWI aggravated if the driver also drove or operated a vehicle in violation of RSA 265:26, I — the divided-ways statute (driving on the wrong roadway of a divided highway or crossing a physical dividing barrier).

New Hampshire prosecutes impaired driving as DWI under RSA 265-A:2 (0.08 per se, or impairment by alcohol, controlled drugs, prescription drugs, over-the-counter drugs, or other chemical substances). Aggravated DWI (RSA 265-A:3) is triggered by a BAC of 0.16+, OR by impairment/0.08 PLUS speeding +30 mph, causing serious bodily injury, eluding an officer, transporting a passenger under 16, or driving a CMV ≥10,001 lbs. The penalty ladder (RSA 265-A:18) climbs from a class B misdemeanor first offense ($500+, 9-mo revocation) through aggravated DWI (class A misdemeanor, 17 days/5 served, 18-mo revocation, IID) and aggravated DWI with injury (class B felony, 35 days/14 served), to a felony at the fourth offense within 10 years. A 10-year lookback governs escalation, with a 2-year sub-window for the 2nd-offense mandatory minimum (60 days/30 served vs. 17 days/5 served). IID is mandatory for aggravated DWI and discretionary for standard first offenses as a condition of sentence reduction. Refusal triggers an administrative suspension (180 days / 2 years) running consecutively to any court penalty. Under-21 offenders face a 0.02 threshold and a minimum 1-year revocation. DUI causing death is the class A felony of negligent homicide (RSA 630:3, II), carrying indefinite license revocation.

New Hampshire DWI penalties by offense tier

Offense tier	Fine	Jail	License action	Ignition interlock
First offense (class B misdemeanor through class B felony)	$500–$1,200 (Mandatory minimum $500 fine (RSA 265-A:18, I(a)(2)).; Class B misdemeanor fine ceiling is $1,200 (RSA 651:2, I).)	0 days–7 years (No mandatory minimum jail for a standard first offense (RSA 265-A:18, I(a)). The court may impose up to 0 days for a class B misdemeanor. AGGRAVATED DWI (§ 265-A:18, I(b)) carries a mandatory 17 days (5 served after 12 suspended). AGGRAVATED DWI WITH SERIOUS BODILY INJURY (§ 265-A:18, I(c)) is a class B felony carrying a mandatory 35 days (14 served after 21 suspended).; Standard first (class B misdemeanor): no jail exposure. Aggravated DWI (class A misdemeanor): up to 12 months. Aggravated DWI with serious bodily injury (class B felony): up to 7 years (RSA 651:2, I).)	Revoked for 270–730 days — STANDARD FIRST (§ 265-A:18, I(a)(6)(A)): license revoked ≥9 months (court may extend to 2 years); up to 6 months may be suspended if the offender is screened within 14 days, completes any required evaluation, completes the impaired-driver education program, and (at the court’s discretion) installs an IID under RSA 265-A:36. AGGRAVATED DWI (§ 265-A:18, I(b)(5)(A)): ≥18 months revocation. AGGRAVATED DWI WITH INJURY (§ 265-A:18, I(c)(5)(A)): ≥18 months revocation. Under-21 offenders serve ≥1 year (§ 265-A:18, III).	Required if restricted license or restoration, BAC ≥ 0.16, or injury to another person (6 months–2 years)
Second offense within 10 years (class A misdemeanor)	$750–$2,000 (Mandatory minimum $750 fine (RSA 265-A:18, IV(a)(2)).; Class A misdemeanor fine ceiling is $2,000 (RSA 651:2, I).)	5 days–1 year (MANDATORY MINIMUM depends on the gap to the prior: 60 consecutive days (30 served) if the prior was within 2 years (§ 265-A:18, IV(a)(3)(A)); 17 consecutive days (5 served) if the prior was 2–10 years (§ 265-A:18, IV(a)(3)(B)). The structured min (5 days) captures the lower (2–10-yr) sub-case; the notes document the higher (within-2-yr) 30-served sub-case.; Class A misdemeanor max 12 months (RSA 651:2, I).)	Revoked for 1095 days — Mandatory 3-year revocation (RSA 265-A:18, IV(a)(4)), not restorable until the IDCMP service plan is complete and all fees paid.	Required if restricted license or restoration (1 year)
Third+ offense within 10 years (class A misdemeanor or felony)	$750–$4,000 (Third offense: $750+ (RSA 265-A:18, IV(b) adopts IV(a) penalties). Felony (4th+): governed by RSA 651:2.; Felony fine ceiling $4,000 (RSA 651:2, I).)	1 month–7 years (THIRD offense (§ 265-A:18, IV(b)(2)): mandatory 180 days (30 served after 150 suspended; remainder deferrable up to 2 years). FOURTH+ (§ 265-A:18, IV(c)): the person "shall be guilty of a felony" — sentencing per RSA 651:2 (class B felony up to 7 years; the statute does not fix a specific class). The structured min (30 days) captures the third-offense served minimum; the felony sub-case carries felony-sentencing exposure under RSA 651:2.; Third offense class A misdemeanor max 12 months. Fourth+ felony: up to 7 years (class B felony, RSA 651:2, I) or higher if charged as class A felony negligent homicide under § 630:3, II (up to 15 years).)	Revoked for 1825–3650 days — INDEFINITE-but-restorable revocation (not a lifetime bar). THIRD offense (§ 265-A:18, IV(b)(1)): not restorable for at least 5 years (1,825 days; court petition required). FOURTH+ (§ 265-A:18, IV(c)): not restorable for at least 7 years. If a prior was negligent-homicide-by-DUI (§ 630:3, II): not restorable for at least 10 years (§ 265-A:18, IV(d)). The structured max (3,650 days = 10 yr) reflects the negligent-homicide-prior floor; restoration is by court petition after the floor.	Required if restricted license or restoration (1 year)

Frequently asked questions

What is the legal BAC limit in New Hampshire?

The per se limit is 0.08% (RSA 265-A:2, I(b)). The offense also covers impairment by alcohol, controlled drugs, prescription drugs, over-the-counter drugs, or other chemical substances. A BAC of 0.16+ is aggravated DWI (RSA 265-A:3, III). The under-21 threshold is 0.02%.

What are the penalties for a first DWI in New Hampshire?

A standard first offense is a class B misdemeanor (RSA 265-A:18, I(a)): $500+ fine, 9-month–2-year license revocation (up to 6 months suspendable with treatment + optional IID), an impaired-driver education program, and IDCMP screening. Effective Jan. 1, 2026, first offenders must also complete a qualified online victim-impact-panel program unless the court finds exceptional circumstances (§ 265-A:18, I(a)(4-a)). AGGRAVATED DWI (e.g. BAC ≥ 0.16) is a class A misdemeanor: $750+, 17 days (5 served), 18-month revocation, mandatory IID. AGGRAVATED DWI with serious bodily injury is a class B felony: $1,000+, 35 days (14 served).

What are the penalties for a second DWI in New Hampshire?

A second offense within 10 years is a class A misdemeanor (RSA 265-A:18, IV(a)): $750+ fine, mandatory 3-year license revocation, and a mandatory jail term of 60 days (30 served) if the prior was within 2 years, or 17 days (5 served) if the prior was 2–10 years prior. Effective Jan. 1, 2026, second offenders must also complete a qualified online victim-impact-panel program unless the court finds exceptional circumstances (§ 265-A:18, IV(a)(3-a)).

When does a New Hampshire DWI become a felony?

A FOURTH offense within 10 years is a felony with indefinite license revocation (≥7 years before petition) under RSA 265-A:18, IV(c). Aggravated DWI causing serious bodily injury is a class B felony at any offense count (§ 265-A:18, I(c)). DUI causing death is the class A felony of negligent homicide (RSA 630:3, II).

Does New Hampshire require an ignition interlock device after a DWI?

IID is MANDATORY for aggravated DWI (including a BAC of 0.16+) under RSA 265-A:18, I(b)(4)/(c)(4) and RSA 265-A:36. For a standard first offense, the court MAY require IID as a condition of suspending up to 6 months of the revocation period.

What happens if I refuse the breath or blood test in New Hampshire?

Refusing a chemical test triggers an administrative license suspension under RSA 265-A:14: 180 days for a first refusal, or 2 years if you have a prior DWI/aggravated-DWI conviction or a prior refusal. The suspension runs consecutively to any court-ordered penalty. Refusal is not a separate crime.

How long do prior DWIs count against me in New Hampshire?

New Hampshire uses a 10-year lookback window (RSA 265-A:18, IV). For a second offense, a 2-year sub-window applies: a prior within 2 years triggers 60 days (30 served), while a prior 2–10 years triggers 17 days (5 served). Out-of-state reasonably-equivalent convictions count.

What is New Hampshire's under-21 BAC rule?

Under RSA 265-A:2, I(b), a driver under 21 is over the limit at a BAC of 0.02 or above. An under-21 offender serves the standard penalty for the offense PLUS a minimum 1-year license revocation (RSA 265-A:18, III).

What if my New Hampshire DWI causes injury or death?

Aggravated DWI causing serious bodily injury is a class B felony (RSA 265-A:18, I(c)): $1,000+ fine, 35 days (14 served), 18-month revocation, mandatory IID. DUI causing death is the class A felony of negligent homicide (RSA 630:3, II), carrying indefinite license revocation (≥7 years before petition) and up to 5 years of IID as a restoration condition.

Sources

RSA § 265-A:14 — Refusal of Consent (N.H. Rev. Stat., via Justia) — Accessed July 7, 2026
RSA § 265-A:18 — Penalties for Intoxication or Under Influence of Drugs Offenses (N.H. Rev. Stat., via Justia) — Accessed July 7, 2026
RSA § 265-A:2 — Driving or Operating Under Influence of Drugs or Liquor; Excess Alcohol Concentration (N.H. Rev. Stat., via Justia) — Accessed July 7, 2026
RSA § 265-A:3 — Aggravated Driving While Intoxicated (N.H. Rev. Stat., via Justia) — Accessed July 7, 2026
RSA § 265-A:36 — Ignition Interlock Device (N.H. Rev. Stat., via Justia) — Accessed July 7, 2026
RSA § 265-A:4 — Implied Consent to Testing (N.H. Rev. Stat., via Justia) — Accessed July 7, 2026
RSA § 630:3 — Negligent Homicide (N.H. Rev. Stat., via Justia) — Accessed July 7, 2026
RSA § 651:2 — Sentences for Felonies and Misdemeanors (N.H. Rev. Stat., via Justia) — Accessed July 7, 2026

New Hampshire DWI Laws

Frequently asked questions

Sources

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