I put in a certain amount for tution fees and turbotax automatically increases by almost $1700 as an additional amount claimed. Why?

(1) When you say "increases" do you mean that the tax owing, or the tax to be refunded, has been increased? (2) Did you also indicate that you are a full or part/time student?

Aside from your tuition fees, you are also allowed the education and textbook amounts.  The education amount is $400/mo for each month that you were in full-time attendance or $120/mo while in part-time attendance.  The textbook amount is $65/mo for full-time attendance or $20/mo for part-time attendance.  While you must have an official receipt confirming your eligible tuition fees and the number of months you were in full-time or part-time attendance, no other receipts are required in this regard.  TurboTax automatically calculates these amounts based on the info you provided from your tuition fee receipt.  For more info, please see http://www.cra-arc.gc.ca/tx/ndvdls/tpcs/ncm-tx/rtrn/cmpltng/ddctns/lns300-350/323/menu-eng.html

Thanks. This was really helpful. I haven't been a student in the longest time and was caught off guard when my claim went up without explanation and then Turbotax gave me a warning that my tuition claim was high enough to result in an audit! I appreciate your answer.