I made a 2009 estimated state tax payment in 2008 of $5,000. I will owe no state tax, so I will be getting a full refund in 2009. I also owe no federal tax, even without the $5,000 state tax deduction.
If 2009 turns out better and I have to pay federal tax, will the $5,000 state tax refund be taxable? It shouldn't be, since I didn't get any tax benefit on the payment so why should I pay tax on the refund, but you never know.
Odds are it will be moot, since 2009 doesn't look any better at this point, but you never know.