Why can't I choice between the Tuition and Fees Deduction and the American Opportunity Credit. The first one seems to give me a higher deduction?

TurboTax will give you the credit or deduction that generates the highest tax benefit for you.  If the student is in the first four years of college while working towards a degree, they are entitled to the American Opportunity Tax Credit.  A part of this credit could be refundable.  

Please see the links below for more details on the credits as well as the Tuition & Fees Deduction.

Chart comparing credits

Tuition & fees deduction

Type letme (no space between let & me) in the search box. Then press enter. Then  click  "jump to letme''. 

TT will give you the option to select another tuition  credit or deduction.

It's highly unlikely that the Tuition and Fees Deduction (TFD) would come out better than  the American Opportunity Credit (AOTC).  The AOTC is a 100% credit on the 1st $2000 of qualified expenses and 25% on the 2nd $2000. Whereas, the TFD is only an (up to) $4000 deduction from income before tax is calculated.

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