1099 and opening and contributing to non roth solo 401k

hello,

 

I have 1099-misc income. I know I can max out 401k (plus catchup)  with solo401k. I think, on top of IRS limit, i can contribute  20% of my 1099 income. So if I have 50k 1099 income and if i am above 50, I can put 26k my contribution, plus 10k as 20% income from employer to sole 401k, (total 36k) right? Which IRS form this employer contribution reported to? I didn't see it on sch C (may be I missed it..)

To open solo 401k do I have to have my onw EIN? or can I use my spouse solo 401k account (or spouse's EIN to setup my own solo 401k?), as we file taxes jointly?

Any idea when solo 401k account must be opened and contributed to, in order to be valid for 2020?

Thanks

 

S