How a violation moves your SMS measure

Severity and the out-of-service addition

Start with the severity weight recorded for the violation and add any recorded out-of-service severity weight. The public violation-code pages show observed weights from the SMS violations file, with their snapshot date.

The cap comes before the time weight

FMCSA's SMS Methodology, version 3.21, caps the sum of severity weights, including applicable OOS additions, at 30 per inspection and BASIC before applying time weight. Weights from other BASICs do not enter that cap. Synthetic example: a severity sum of 40 at ×3 contributes 30 × 3 = 90 to the numerator; capping after multiplication would give 30 instead.

Within each inspection and BASIC, severity weights including any out-of-service additions are summed, capped at 30, and only then multiplied by the time weight. Violations in other BASICs do not enter that cap.

The time bands and calculation window

SMS uses a 24-month inspection window. The time weight is ×3 through 6 months back from the snapshot date, ×2 for more than 6 through 12 months back, and ×1 for more than 12 through 24 months back. Older inspections are outside that snapshot's calculation window.

Read these age bands relative to the snapshot date. They describe that snapshot's calculation, not a promised date for a record to disappear.

A lower time weight reduces an inspection's weighted numerator contribution; it need not lower the measure. For inspection-normalized BASICs, time weight also applies to relevant inspections in the denominator, including inspections with no violation in that BASIC. The result depends on all relevant inspections in the same snapshot; their aging, arrival, or departure can change the denominator too. Exposure-normalized BASICs use a different denominator.

Synthetic arithmetic example for an inspection-normalized BASIC: with one relevant inspection, severity 6 and time weight ×3, the ratio is 18/3 = 6. When its time weight becomes ×2, the ratio is 12/2 = 6. This illustrates normalization only; it does not establish enough data for a published position.

From the numerator to the measure

Add the capped, time-weighted inspection contributions within the BASIC to form its numerator. The denominator depends on the BASIC: relevant inspections for inspection-normalized measures, or exposure for exposure-normalized measures. Relevant inspections with no violation in the BASIC can still enter an inspection denominator.

The measure is the numerator divided by that denominator. Matching a displayed measure does not establish how FMCSA represents the number internally.

What removing one violation changes

If the sum still reaches the 30-point cap after a violation is removed, the inspection's contribution is unchanged. The effect of removing a violation is the difference between the measure with it and the measure without it, keeping the other snapshot data fixed.

A what-if calculation keeps the other data in the current snapshot fixed. It is a calculation of the measure's change, not a prediction of an agency decision.

Sources for these numbers

FMCSA SMS Methodology v3.21, Vehicle Maintenance pp. 3-14–3-15, as used for snapshot 2026-07-31. The linked primary methodology gives the cap, time weights and relevant-inspection denominator; the calculation guide explains marginal contribution.