I have about 5 days of vacation saved up at my current employer. Would it be rude and unprofessional to use them and give my two weeks notice the day I return?
This isn't a question of rudeness. It's a question of two things:
- Have you already accrued* the vacation days? (Given it's the end of the year, I presume the answer is yes, but this is important)
- Does your employer pay out unused vacation upon resigning?
If you've already accrued them, and your employer either doesn't pay them out, or you don't want the money, this is perfectly normal and acceptable behavior.
Provided you give proper notice when you return, there's nothing unprofessional about this.
What may be unprofessional (see comments) would be resigning, and trying to use your vacation as your notice period. In some places, this is normal, in others, this is seen as throwing your team "under the bus". This is role/context/industry dependent.
*For the benefit of others with similar questions, at different times of the year: many companies allow you to take your full year's vacation allocation anytime throughout the year, with the presumption that you will stay. This is usually "accrued" X days/X partial days a month, over the year. If you take more than you've accrued by the day of your resignation, your employer can generally deduct this from your last paycheque.
In many countries, your employer has to pay you for accrued holidays that you didn't take yet, or you have to pay for holidays that you've taken that were not accrued yet. In those countries, taking holidays just before you are leaving just swaps holidays for cash, so you'd do whatever you prefer.
In some places in the USA, employers will refuse to pay you for accrued holidays that you haven't taken yet. If that is your situation, then obviously you will take your holiday instead of giving them as a present to your employer.
In the first case, taking holidays is just normal, in the second case it's not rude and unprofessional but just self defense.
If the time off is yours to use whenever for any reason, then no, it's not rude. Talk with your manager, especially with the holidays, should be easy to take time off.
If it's possible, talk with your manager about leaving. If this is not possible, nor feasible, due to trust issues, etc. then resigning upon your return might be looked upon as unprofessional. So long as you treat all parties with respect, you're doing the professional thing.
Would it be rude and unprofessional to use them and give my two weeks notice the day I return?
Not at all. That's perfectly normal and a sensible thing to do. Most employers do pay our accrued vacation but you still will loose some associated benefits (health insurance, 401k match, etc.)
You've earned it and it's yours to use as you see fit.
Assuming that your employer will have to pay you for unused vacation days, there doesn't seem to be much difference in terms of salary. Either way, you are paid for 3 weeks and have to be in the office for 2 of them.
1) You hand in notice now, work for two weeks starting now, leave after two weeks with a week's pay in your hand from unused vacation, and "do nothing" for a week.
2) You "do nothing" for a week, hand in your notice, and leave two weeks after that with no back-vacation payment (but it was already paid as part of your normal paycheck).
As already mentioned, the first choice means you have at least one week less of whatever non-salary benefits your employer offers. Such benefits might be more than one week - for example, if you have health insurance from the job, and "resign later" pushes your last day into the next month, then maybe that means one more month of coverage. So there's some personal-benefit angle involved, which I suppose could be called "unprofessional".
I however do not see it that way. You're playing the game according to the established rules, not breaking the rules. That is, I find choice 2 perfectly professional. I'd probably make the choice based on my arrangements for the new job, in particular whether I wanted some time off between jobs - choice 1 feels better in that regard since I am still "getting paid" for a one-week buffer.