Rule: Address mismatch

Rule key: address_mismatch · Default weight: 0.8 · Tier: Lite

Compares billing and shipping addresses at three increasingly granular levels. Returns at the first match — a country mismatch short-circuits the state and city checks because once countries differ the rest is implied.

Comparison	Base score	Notes
Country mismatch	50	Strongest signal — classic carder pattern
State mismatch (same country)	15	Often legitimate (multi-state work travel)
City mismatch (same state)	5	Very weak signal, common with gifts

When this rule skips

The rule returns clean (no score) for orders without a shipping address at all — digital-goods orders, \”shipping not required\” cart configurations, and \”ship to billing address\” checkouts where the two addresses are identical.

Caveats

If you sell gifts heavily (greeting-card sites, flower delivery, B2B promotional swag), the country-mismatch signal will fire on legitimate orders. Lower this weight to 0.3–0.4 and lean harder on velocity + behavioural signals instead.