@mysterious-tomato-10057
Dependent Care FSA doesn't work the same as Healthcare FSA.
With a healthcare FSA you have all the money available to you at the beginning of the year and the company deducts the money from your paycheck throughout the year. (Fun fact: If you leave the company and you have a remaining balance in the account you lose it. I*f you leave and you've used more than has currently been deducted the company is not allowed to deduct the remainder. I had a company that tried to do that because I used it all up since I knew I was leaving. Its illegal.*)
With dependent care FSA you can only use money that has already been deducted, so as the year progresses, the balance increases. So if you pay a babysitter $6,000 for 10 months you'll be paying them $600/mo and have 2 months with no payment. However the FSA is deducted on a 12 month basis ($500/mo).
When you then put in a claim for $600 for a month, the FSA will only reimburse $500 since that was what was deducted from your paycheck for that month. The next month they would reimburse the remaining $100 and if you make another $600 claim they would use the remaining $400 towards that claim and so on.