Level 1

Retirement tax questions

Using form 8606 I had contributed to non-deductible IRA  prior to availability of ROTH IRA. I would like to convert to ROTH IRA. Since I have another traditional IRA( this account deductible amount), if I convert this deductible traditional IRA to ROTH IRA  during this year 4th quarter, do I still need to do pro-rata calculation on non-deductible IRA if I convert this non-deductible  to ROTH in 4th quarter as well ? Was thinking since I converted my only taxable IRA to ROTH IRA, no need to pro-rata and pay no tax this year for this non-deductible amount.