While I am no tax expert, typically those fees are deductible from gross income on their tax returns as business expenses, however, with the amount your 4/c made in 2014, it won't matter. Your 4/C should get back 100% of the amount held out for his taxes for 2014 with or without the deductions you mentioned. (Assuming that he has no other income source like investment income, job prior to the CG, etc). If the CG was his only source of income, he should get a tax refund of all of the amount the CG withheld from his pay.
Next year, this could be different considering the expenses they are required to pay. I know there is much discussion on this topic, but for most, this will be the last year that the 4/C's can be claimed as dependents by their parents.
Again, if you have any questions, I'd encourage you to speak with a tax professional. There will be assistance offered to the Cadets if they are doing their own taxes. Just be sure that as a parent you don't claim him/her as a dependent if in fact they are claiming themselves.
Hope this helps.
