Tax day is approaching and you may be looking for additional deductions for 2015. Can you still make a deductible contribution to your 529 plan? It depends.

Since 529 contributions are only deductible at the state level (and only in states that have a tax deduction for the contributions), each state sets its own deadline. Fortunately it’s not as arbitrary as that sounds: generally, states either require the contribution to be made by Dec. 31 of the tax year (like your 401(k)) or by the date you file your taxes (like an IRA).

In addition, states have their own rules about who can take the deduction. Some states only give the deduction to the account owner; others let the person who makes the contribution, regardless of who owns the account to which is being contributed, take the deduction.

This is an important distinction for grandparents and other non-parent contributors when the student beneficiary is likely to be aid eligible. Remember that only parent-owned 529 accounts are reported as (parent) assets on the FAFSA, but distributions from non-parent-owned 529 accounts are reported as (student) income on the FAFSA. Given that parent assets only count for 5.6% to the extent that they exceed the Asset Protection Allowance (about $19,000 for married parents),  if it’s possible for the grandparents to get the deduction for contributing to the parents’ account, that’s usually the best route.

Again, every state has its own rules so be sure to check yours before deciding whether, how much and to what account to contribute if the 2015 tax deduction is your primary motivation.