Market Data

Effective vs Statutory Tariff Rates: Why the Two Measures Differ

The tariff schedule's unweighted line rates and an observed calculated-duty rate are different measures. Understanding the gap prevents an aggregate statistic from being mistaken for an entry quote.

The Harmonized Tariff Schedule reports General-column rates by HTS line; for heading 7318 the tracked MFN range is 0%–12.5%. USITC DataWeb reports a different aggregate: Calculated Duties equal to 35.91% of customs value covered by those duty observations in 2025. Their gap can reflect product, origin, preference, exclusion, and other entry mix. It is descriptive, not a Section 301/232 decomposition or an entry-specific quote.

• General line range, fasteners (HTS 2026): 0%–12.5%
• Observed calculated-duty rate, 2025: 35.91%
• Change vs prior reported year: +29.4 points

The observed effective rate is USITC's reported calculated duty divided by customs value for imports for consumption. It summarizes the recorded mix without identifying which legal provision caused the difference. Across the 57 manufacturing import families MFG Calcs tracks, USITC reported an average effective calculated-duty rate of 12.4% of customs value covered by those duty observations in 2025, versus 3.3% the year before.

The statutory schedule and observed effective rate answer different questions. Use the aggregate rate for context, then verify the actual classification, origin, program eligibility, and Chapter 99 applicability for the entry.

How to use each number

• General-column MFN: the statutory line reference for Normal Trade Relations origins, not a final entry quote.
• Special-program Free rates: potential treatment only when eligibility, rules of origin, and a valid claim are established.
• Observed effective and per-country rates: aggregate planning context for the recorded mix, not entry-specific legal rates or cash-payment records.

Every family page in the MFG Calcs Tariff Monitor shows both columns side by side with top source countries, and the numbers refresh automatically as USITC publishes. Reference statistics derived from USITC published data. Not a customs ruling. MFN-Free and Special-rate fields describe statutory line coverage only; final entry liability requires origin, date, eligibility, exclusions and other transaction facts. Calculated Duties are statistical estimates, not a cash-collections ledger. Confirm classification, origin, program eligibility, and final entry liability with a licensed customs broker.

Statutory and effective rates for 57 manufacturing families, with source-country breakdowns. Look up your product family

Published 2026-07-19.