We tried filing jointly and separately this year to see which can save us more money. And we find when we file separately, TurboTax seems to apply all the AMT credit to one of us, while when we file jointly, we can't use all the credits, so overall we are paying more taxes. I was wondering if this is something we can do?
Just because you paid AMT last year, does not mean that you can claim a credit
for the AMT you paid last year. You can only claim an AMT credit for timing or
deferral items that caused you to be in AMT in a prior year. Timing or
deferral items are typically caused by the exercise of incentive stock options
or depreciation difference.
As you did not have timing differences, you should not be taking a AMT credit.