Do charitable contributions not lower your Modified Adustable Gross Income?

CORRECTION:

AGI and MAGI are calculated before any itemized deductions, such as charitable contributions, are applied. Itemized deductions do not reduce AGI or MAGI.

Secondly, MAGI is calculated differently for different purposes. There are about a dozen different definitions of MAGI, depending on what it's being used for. You didn't say which MAGI you are looking at.

The first reply that I posted was wrong. AGI and MAGI are calculated before any itemized deductions, such as charitable contributions, are applied. Itemized deductions do not reduce AGI or MAGI under any circumstances. I have corrected my first reply above.