Thanks very much for the feedback, mia and Antipode. What I might do in 2010, unless folks advise me differently, is use my CC to pay more in estimated taxes in 2010 than I will ultimately owe when it comes to pay my 2010 taxes in 2011. IIRC, I've inadvertently done this in a minor way in the past with state taxes and the refund went into my back account. I'll need to check this option out more on my own, but if anyone has any further advice about this I'd welcome it. And I am aware of the extra charge for CC use to pay taxes, not to mention the opportunity costs of leaving that extra money parked in state and/or federal coffers until its refunded.