I have received a form 705 from DFAS. The overpayment by Department of Defense established as a debt repayment. I paid $608.18. Can I use it as miscellaneous deduction?

Yes, you can deduct your DFAS repayment as as Miscellaneous Deduction.

Here is a data entry for repayment of $3000 or less:

1. Federal Taxes
2. Deductions & Credits
3. Other Deductions & Credits, select Other Deductible Expenses,  select No to Generation Skipping tax question and No to Less Common Expenses, Yes to Any other Deductions that are not subject to the 2 % limitation, enter description Repayment DFAS Form 705 and the amount.

For repayment on $3000 or more, you may use the deduction instructions above or you may also figure out the credit. Please click here.  To make that choice, use the method (deduction above or credit explained below) that results in less tax. You won't be able to do it online, cd/download would be needed.

Your 2nd question: your parents can claim 1098-T only if they claim you as their dependent.