Tariff monitor · Machinery & Equipment

Internal Combustion Engines: Statutory & Effective Tariff Rates

Statutory HTS duty rates for 37 internal combustion engines tariff lines (MFN Free–2.5%), from USITC. Effective rate May 2026: 7.52%; monthly history since 2014.

The short answer

  • The effective U.S. tariff on internal combustion engines was 7.52% in May 2026, down from 13.84% a year earlier — calculated duties actually paid divided by customs value, from USITC data. The statutory MFN rate is Free–2.5% across 37 HTS lines in the 2026 schedule. Mexico is the largest source, holding 35.9% of 2025 imports.

Statutory rates from the schedule

  • Gasoline and diesel piston engines and their parts — prime movers for gensets, pumps, compressors, and mobile equipment. This family covers HTS headings 8407, 8408, 8409: 37 eight-digit rate lines with MFN (column 1, general) rates of Free–2.5% in the 2026 schedule.
  • Chapter 99 flags on individual lines mark Section 301/232 overlay provisions (e.g. 9903.88.01) that apply on top of the MFN column.

What importers actually paid

  • Latest month on record (2026-05): 7.52% effective on $2.5B of imports, versus 13.84% in the same month a year earlier. The monthly archive holds 149 observations from 2014-01 through 2026-05.
  • In 2025, U.S. imports for consumption in this family totaled $27.7B in customs value and paid $3.5B in calculated duties: an effective tariff rate of 12.59%. The effective rate captures Section 301/232 overlays, exclusions, and special-program use that the statutory column cannot.
  • A year earlier the effective rate was 2.29%, so the duty burden rose 10.3 points.
  • Top source countries in 2025: Mexico ($9.9B at 9.31%), Japan ($3.7B at 13.7%), Canada ($3.4B at 2.71%), Germany ($2.1B at 14.32%), South Korea ($1.7B at 7.59%).

Representative rate lines

  • 8407.10.00: Aircraft engines · MFN Free
  • 8407.21.00: Outboard motors · MFN Free
  • 8407.29.00: Other · MFN Free
  • 8407.31.00: Of a cylinder capacity not exceeding 50 cc · MFN Free
  • 8407.32.10.00: To be installed in tractors suitable for agricultural use · MFN Free
  • 8407.32.20: To be installed in vehicles of subheading 8701.21, 8701.22, 8701.23, 8701.24 or 8701.29, o · MFN Free
  • 8407.32.90: Other · MFN Free
  • 8407.33.10: To be installed in tractors suitable for agricultural use · MFN Free

Frequently asked questions

  • What is the U.S. tariff rate on internal combustion engines? Importers paid an effective rate of 7.52% in May 2026 (calculated duties ÷ customs value, USITC DataWeb). The statutory MFN rate is Free–2.5%; Section 301/232 overlays and special programs explain the difference.
  • What is the statutory MFN duty rate for internal combustion engines? Free–2.5% across the family's 37 eight-digit HTS lines in the 2026 Harmonized Tariff Schedule (headings 8407, 8408, 8409).
  • Which countries supply the most internal combustion engines to the U.S.? Top sources in 2025: Mexico ($9.9B at 9.31%), Japan ($3.7B at 13.7%), Canada ($3.4B at 2.71%). Sourcing is moderately concentrated: Mexico holds 35.9% of imports.
  • How much internal combustion engines does the U.S. import? $27.7B of customs value in 2025, paying $3.5B in calculated duties — an effective tariff of 12.59%.
  • Is the U.S. a net importer of internal combustion engines? Yes — a net importer in 2025: $27.7B imported vs $8.8B exported (exports are 32% of imports).

About this data

  • Reference statistics derived from USITC published data. Not a customs ruling; verify rates with a licensed customs broker before relying on them.

Last reviewed 2026-05-12.