ANSWER:
No, as just like IRA to Roth IRA conversions, the conversion of solo 401k funds (wether pretax or after tax funds) to a Roth IRA or to the Roth solo 401k for that matter are reportable for the year in which the funds or assets are actually converted. You can’t proess a conversion this year and count as a conversion occurng in the prior year(s), for example.
What is more, per the IRS rules in order to convert pretax solo 401k funds to a Roth IRA, you have to be age 59 1/2 or older. However, if you are converting pretax solo 401k funds that stem from IRA funds that were previously transferred to the solo 401k plan, those can be converted this year to a Roth IRA. If you qualify based on the aforementioned, see the following regarding processing a conversion of pretax solo 401k funds to a Roth IRA. https://www.mysolo401k.net/pretax-solo-401k-to-roth-ira-conversion-form/
