My personal exemption went from $10,240 to $2,916. Why such a huge drop? Only difference is that one of my two children had summer internship income greater than $6000.

Without examining your return, it's impossible to say exactly what caused your personal exemption to decrease. However, there's a high probability that at least one reason is listed below.

If your refund is wildly off, it's possible you simply mistyped a dollar amount somewhere. An extra digit here, a missing number there, even something as seemingly insignificant as a misplaced decimal point can have an eye-popping effect on your TurboTax refund.

Changes in your income or tax rate

• You (or your spouse) took on an additional job (especially non-wage income which is taxed at the higher self-employment tax rate);
• Your salary or wages increased but your W-4 stayed the same;
• You sold investments but didn't take out any taxes from the sale;
• Your filing status changed from last year;
• You started receiving Social Security benefits or Roth IRA distributions;
• You received taxable unemployment income;
• You had gambling winnings;
• You're paying a penalty for not having health insurance coverage in 2016.

Loss of credits or deductions

• Your child turned 17 in 2016, causing you to lose the $1,000 Child Tax Credit;
• Your child turned 19 in 2016 (or 24, if a full-time student) and no longer qualifies as a dependent;
• You paid off your mortgage and can no longer deduct mortgage interest;
• You took the itemized deduction last year (for example because of high medical bills) but got the standard deduction this year;
• You didn't qualify for the Earned Income Credit this year;
• You paid off your student loan and can no longer deduct the interest;
• You're no longer eligible for certain education credits (or you took a different credit this year)
• You didn't contribute to a Traditional IRA (or couldn't take the full deduction because your income was too high).