Here's how I'm figuring our flex spending acct works with dd's braces that were just put on a few weeks ago:
We have $80 taken out of dh's check twice a month, so at the beginning of our flex spending acct time (ours is June 1 - May 31), are FSA has a balance of $1920. We gave the ortho $1000 from there, and saved the rest for other medical needs that will come up, like copays, medicine, etc. Whatever money I have leftover when it gets close to May 31, I'll just give to the ortho. Now, when June 1, 2011 comes we'll get another $1920 in our FSA and I'll give the ortho probably $1500 this time. So, our balance will then be around $1500 more. Then on June 1, 2012, we'll get another $1920 into our FSA account, and I'll pay the ortho off. DD just got her braces on Jan 3, 2011, and she's supposed to have them on for 20 months. So, hopefully this will all work out with the FSA! lol.
The one thing I didn't know in advance about our FSA is that you have access to the money on the first day of your plan. You don't have to wait until the money is deposited each payday to have access to it. KWIM?
HTH