Ever since electronic permits for foreign travelers to the United States who don’t need a regular visa became mandatory in January, I’ve been getting reports about confusion among both passengers and airport agents about some of the new rules. So I thought I’d try to clear things up.

It’s a particularly good time to do that, because after March 20, the Department of Homeland Security will impose fines on airlines that transport visitors with neither a visa in their passport nor approval by the new Electronic System for Travel Authorization (ESTA). The fines will be $3,300 for each non-compliant passenger…