Question about Solo Roth 401(k) plan and contribution rules - please help

Hello I recently opened a Roth Solo 401(k) account with Vanguard. I am self-employed with a single member LLC that has passthrough taxation. This year of 2023 we are expecting the business to show a loss and thus show a loss on the tax return which will show a loss for my personal tax return because of the passthrough taxation. Am I allowed to contribute to my Roth Solo 401(k) plan if my tax return shows no income? What happens if I contribute to the 401(k) now, then discover in January of next year that we indeed had a loss in 2023? 

 

Question 2: is it too late to contribute to my Roth Solo 401(k) plan for the year of 2022? 


Thank you for any help on this!