Looking for advice on relocating my online mentoring business!

Hi everyone,
I’m currently based in Poland and work full-time for a company here. In addition to that, I run a small mentoring business where almost all of my clients are from Spain (I’m Spanish myself), so still within the EU but in a different country.

The issue is that when I combine the accounting of both activities, I cross one of Poland’s tax thresholds, which forces me into a much more expensive regime. The tax burden becomes extremely high, even though my mentoring business is small and 100% online.

I’m trying to figure out whether there is any legal and sensible way to register or relocate this online mentoring business to another jurisdiction, ideally one that is friendly to digital services, doesn’t punish small EU-based online businesses, and won’t conflict with Polish residency rules.

I don’t have clients in Poland, and the business is 100% online. It’s basically an online education service for Spanish clients.

Has anyone dealt with something similar or has recommendations on:

• registering an online business abroad while living in Poland,
• jurisdictions commonly used for EU-based digital education businesses,
• Some people recommended me Estonia

Any advice, experiences or pointers would be really appreciated. I’m just trying to avoid being forced into a tax regime that makes the business barely viable.

Thanks in advance!