IRS is very clear on tax treatment of personal expenses. They are not tax deductible even if they are work-related, like eating out on business trips. The only way 50% of that dinner is tax deductible is if you have a client with you and the express purpose of that dinner is to discuss business. The same does not hold true for a member of the armed forces. Even if this member is eating out alone on a dinner that is part of a professional club, he can deduct the cost of that dinner.
The business side of a Military life is a lot different than anything you might experience in another business. There is a very thin line between what constitutes a social expense versus a business expense. Social expense is things like membership dues for social clubs that are voluntary to attend. Business expense is a professionals dinner that you have to attend as part of your job, like an officers dinner. If you dont attend this dinner it might have an effect on your job. Now for someone who is looking in from the outside, both of these events seem similar but what makes them different is how much control does the member of the armed forces have over attendance.
If the event requires the taxpayer to be present, meaning he/she has to be there as part of his job even though its just a dinner, which makes the dinner expenses tax deductible. Another good example of this would be an event thrown as part of the one-year anniversary of the induction of a colonel as president of the officers club, colonels expenses here are tax deductible because non-attendance would have a negative effect on the colonels career in the military. But the dues to this Officers club are not tax deductible. Anyone attending this event, his or her expenses are not tax deductible because the event was thrown, as anniversary for the induction of the colonel, so the only person required to be there was the colonel.
Any event or party that is thrown by members of a social club in the military with attendance being voluntary, any expenses incurred at such a event are not tax deductible because they are more for personal gain not professional. If the taxpayer doesnt attend this event or party, it would not adversely affect his job.
So basically entertainment expenses that are work-related are tax deductible like going to parties or attending meetings of social clubs that are part of the business side of the military life but any event or party that you attend for pleasure is part of the social side of the military life, hence not tax deductible.