deadline date

Is it still possible to set up a solo 401k for a sole proprietor.

I thought someone had told me that under the Cares Act there was additional time to do so.

Appears you can set up a solo 401k up until the due date of the 2021 return, including extensions.

However, that is only for the employer match portion.

If you wanted to contribute the $19,500 portion, had to set up the plan by 12/31/21.

Question: can i have a SEP contribution for 2021 for 19,500 and the employer match portion for $38,500

I'm thinking no.

The EE portion can be made by the due date of the return including extensions as well.

The client just needs to elect to make the EE deferral by year-end, not actually transfer the cash.

one catch is that i'm reading to make the ee portion at all, you have to have the solo 401k set up by 12/31/xx

The EE portion can be made by the due date of the return including extensions as well.

The client just needs to elect to make the EE deferral by year-end, not actually transfer the cash.

What is the mechanics of "electing" to make the EE deferral by year-end? i.e. how and where to elect? Thanks.

The client just needs to elect to make the EE deferral by year-end

And that can only be done if a plan was in place by Dec 31.
You can establish the plan after Dec 31 but will be limited to the ER contribution.

Not authority:
https://www.irahelp.com/slottreport/123121-deadline-may-loom-starting-new-solo-401k-plan#:~:text=There%20is%20a%20December%2031,employer%20contributions%20as%20an%20employer.

Pub 560:

Employee Contributions
Participants may be permitted to make nondeductible contributions to a plan in addition to your contributions. Even though these employee contributions aren't deductible, the earnings on them are tax free until distributed in later years. Also, these contributions must satisfy the actual contribution percentage (ACP) test of section 401(m)(2), a nondiscrimination test that applies to employee contributions and matching contributions. See Regulations sections 1.401(k)-2 and 1.401(m)-2 for further guidance relating to the nondiscrimination rules under sections 401(k) and 401(m).

When Contributions Are Considered Made
You generally apply your plan contributions to the year in which you make them. But you can apply them to the previous year if all the following requirements are met.

You make them by the due date of your tax return for the previous year (plus extensions).
The plan was established by the end of the previous year.