I did some research into this but depending on the scale of your company I may or may not be worth it. Assuming you keep on being a tax residence in Spain you will pay income tax there regardless (possibly dividend tax). The thing that might be cheaper is the corporate tax rate. I don't know what the rate in Spain is but for my situation it just simply wasn't worth it to save a few % of tax but going through the hassle of setting up a company in a remote foreign country.

Of course, for me a few % was a few thousand euros which would be lost again by the additional costs, but if you scale up it might be interesting.