N.S.
If you spend a lot on childcare then the FSA will probably be better than using the tax credit. The way you can figure out how much you'll save is by crunching the numbers. You can get the tax table and childcare tax credit form on irs.gov. Hypothetically, say you make $100,000 a year and you pay $5,000 in childcare. So you would end up paying taxes on $95,000 instead of $100,000. To make it simple, say you're in the 25% tax bracket, so instead of paying $25,000 in taxes you would pay $23,750 for a savings of $1,250. Compare that to the tax credit where I think you only get a max of 20% back, in this scenario, 20% of $5,000 would be $1,000, so you would save more money using the FSA.
What we did was divide how much we would spend by 24 and that's how much we had deducted from each paycheck since we get paid twice a month. We faxed our receipt and the claim form every 3 months to get reimbursed.