Basically you select an amount out of your yearly salary, that money doesn't get taxed and you can use it on medical bills.

So let's say you pick $2600. You are available right away to spend that $2600 right on 1/1/23.

They will deduct $50 a week or $100 every 2 weeks based on how often you get paid.

But if you don't spend it all in 2023 , you lose in 2024.

Most plans have a grace period a couple months into the new year.

So if you are paid 50k a year, your net taxable income would be 47.4k