What Is Minimum Wage?
Minimum wage is simply the lowest amount you're allowed to pay someone for an hour of work. Simple idea, messy in practice, because "minimum wage" doesn't mean one single number. There's a federal rate, then each state sets its own on top of that, usually higher, and some cities pile on a local rate too. Whichever number is highest where your employee actually works, that's the one that's legally binding.
Restaurants deal with an extra wrinkle here. Tipped workers, servers and bartenders mostly, can legally be paid a lower cash wage, as long as their tips make up the difference and get them to full minimum wage. Sounds fine on paper, but on a dead Tuesday night when tips are thin, you're the one who has to cover the gap. Skip that, even without realizing it, and you've got a wage violation on your hands.
It gets messier fast if you've got locations in different states. Pay that's perfectly legal in one city might be underpaying someone at a location twenty miles away. And these rates don't stay still, most change every year or so, which means what worked last January might already be wrong.
Honestly, trying to track all of this by hand across multiple locations is asking for a mistake. That's why a lot of multi-location businesses use payroll software that applies the correct rate automatically based on exactly where each person works.