I am currently paying an installment plan that has 2 consecutive years combined into it. For the earlier year, I owe almost $1,000.00 more than the more recent tax year. My question is, when I go to Direct Pay to make my monthly payment, which tax year should I indicate I am paying for, the earlier year or the more recent year? Or does it even matter? I'm curious, because clearly the older debt has the potential to cost me more in interest and failure to pay penalties.