BSGBoosterSeatGuide

State law page

Washington Booster Seat Laws & Requirements (2026)

Under 2 years – rear-facing child restraint | 2 to 4 years – child restraint with harness (rear or forward-facing) | 4 years and older – car or booster seat until 4’9” | Up to age 13 years – must ride in back seat when practical

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FieldWashington snapshot
Age requirementUnder 2 years – rear-facing child restraint | 2 to 4 years – child restraint with harness (rear or forward-facing) | 4 years and older – car or booster seat until 4’9” | Up to age 13 years – must ride in back seat when practical
Height requirementSee child-restraint rule; includes height language where listed.
Weight requirementNo weight threshold listed in GHSA summary.
Fine / penaltyVerify fine with state source; GHSA notes first-offense fines vary by state.
Last checkedGHSA reviewed by SHSOs June 2025; extracted 2026-07-23
Verification levelIndex source; official state verification pending
Child restraint requiredUnder 2 years – rear-facing child restraint | 2 to 4 years – child restraint with harness (rear or forward-facing) | 4 years and older – car or booster seat until 4’9” | Up to age 13 years – must ride in back seat when practical
Adult safety belt permissible4’9” or taller | Adult seat belt fits properly | 40 lbs or over in seating position with only lap belt
Verification levelIndex source; official state verification pending

Sources

Law and source links

Index source: https://www.ghsa.org/state-laws-issues/child-passengers

Statute/source text: GHSA child passenger law summary; Safe Kids state law tracker cross-check

Safety guidance

Even when Washington law allows a seat belt, NHTSA, CDC, and AAP guidance may still recommend a booster until the vehicle belt fits properly.

Requirements guide

Understand age, height, weight, and seat belt fit.

Read requirements

Age guide

See when children typically start and stop using boosters.

Read age guide