1.    Adjust your income tax withholding.
2.    Spend expiring funds in your flexible spending account for dependent care, transportation expenses, etc.
3.    Purchase over-the-counter medicines to deplete funds in your healthcare flexible spending account.
4.    Use your annual insurance deductible.  If you have medical expenses, try to schedule the appointment before December 31st.
5.    Decide whether it is to your tax benefit to pay your property taxes in the current year or the following year.