I would like to convert from a traditional IRA to a ROTH as well as make a contribution to it. I was told by my CPA that if I do it in the next few weeks (before April 15) the conversion will count for the tax year 2000 and the contribution will count for the tax year 1999. I have seen no other information on this. Does anyone know if a conversion is according to the tax year or the calendar year?

Actually, they are both on the calendar year. The difference is that the conversion counts for the year of conversion (2000) and the contribution counts for the year it is designated (1999 or 2000, whatever you want). It is not really a fiscal year, but just a rule that lets you designate a contribution made in 2000 as a contribution for 1999.