A good ID check isn't a knack, it's a routine, one your whole staff runs the same way on every guest. Set it up right and each check takes a few seconds and holds up long after.
So this is how to check an ID at a bar as a repeatable system: the method regulators teach, who to screen, what to accept, and how to refuse and record it. It's the standard to train your door on, not a trick for eyeballing a card.
The FLAG method
Most state alcohol boards teach one framework, and California's ABC lays it out cleanly: FLAG, for Feel, Look, Ask, Give back. It's the backbone of the routine.
Everything below is how to build that routine into a policy your staff can run without thinking.
Screen by appearance
You don't card the regular who's clearly in their forties. You do card everyone who could plausibly be underage.
The common house policy is to check anyone who looks under 30. Some venues set it at 35 or 40 to be safe. Pick a number, post it, and hold every staffer to it.
A bright line is the point: it removes the judgment call. Nobody has to decide who "looks 21", they card everyone in the window.
Inspect the card, and the person
FLAG's Feel and Look steps are where a bad ID shows itself, a flimsy or peeling card, off printing, or a photo and physical description that don't match the person holding it.
That's a skill of its own, and it's the whole subject of how to spot a fake ID. For the routine, the rule is short: get it in your hand, check the card and the person together, and slow down on anything that doesn't fit.
Do the age math, and check expiry
This is the step that's easy to fumble at 1am, and the one worth automating.
Read the date of birth against your threshold and confirm the card isn't expired. An expired ID usually isn't valid proof of age, even when it still scans.
A scan does this instantly and the same way every time: it returns a single verdict and flags an expired card, which is how ID scanners work. That frees your staff for the parts only a person can do.
Accept only a valid document
A document you can't accept is a no before you even check the age. A student ID, an expired card, or a photo of an ID on a phone doesn't qualify.
Set your accept-list from your state's rules, a current, government-issued photo ID with a date of birth, and train staff on which forms of ID to accept.
You're never required to serve
Keep this one in your back pocket for the tense moments.
Hand the card back, stay calm, and decline. You don't owe anyone a debate at the door.
Keep the record
The last piece protects the house: a check you can prove beats one you only remember.
Keep the scan, the time, the door, and the age result. It's what supports an affirmative defense and limits dram shop liability, and a good scanner keeps it as a clean record with no name, birthday, or ID number stored.
That's the whole routine: FLAG the card, screen by appearance, accept only valid IDs, do the age math, refuse when you should, and keep the record. Run it the same way on every guest and it holds up, at the door and afterward.
Carded reads the barcode, checks age, flags expired, and catches the passback, then keeps a clean record with no personal details stored, so the age math and the proof are handled and your staff can run the rest of the check. See the ID scanner for bars.