Question about contributing to a Roth Solo 401(k)

[Chris M.]

Hi guys, I am self-employed with a business which is a single member LLC and no employees other than myself and pass-through taxation. I have a question about contributions to a Roth Solo 401(k) plan. If my business shows a loss for the tax year, can I still contribute to the Roth Solo 401(k) or can I only contribute based on the NET income shown on my tax return? For example if the tax return shows $5,000 NET profit, that's the maximum I could contribute to the Roth Solo 401(k) plan?

Thanks for any information on this.