Hey Dave,
Is there a threshold as to when a married couple filing jointly would fall under the AMT?
Alejandro
Alejandro,
Good question, but there is not a threshold, per se. AMT, or Alternative Minimum Tax, is really an alternative method of calculating your tax liability, with certain adjustments being made to your deductions along with other AMT adjustments. The starting point is the same as the "regular" tax system, and that is the Adjusted Gross Income (AGI) on your return. If the AMT calculation is larger than the regular tax calculation, then you will owe AMT taxes.
All that said, the basic exemption amount for 2014 for folks filing Married Filing Jointly is $82,100. That is, if your AGI after the AMT adjustments (also called your "Alternative minimum taxable income") is $82,100 or less, then generally you will not owe AMT taxes. If the Alternative minimum taxable income is above this amount, there is the possibility that you may owe AMT.
You will find more information on the AMT, plus links to other information here.
Deductibly Yours,
Dave