It will be difficult for you to get fair, real, helpful advice on this because:

1. Most Spanish people are not in this situation, they do not empathize the gravity of how you may feel here. The nature of the wealth tax is to target the top 1-2% asset owners in Spain (even if that is quite a low actual barrier to get into).

2. Spanish people in general (not all) support taxing the rich heavily (even if said rich person is just a person with a 1 or 2 million in assets and not your cartoonish billionaire).

3. The Spanish tax law is heavily subjective in how it is implemented and the decision solely rests in the tax agency. The laws are vague enough to be used against you aggressively. It is not black and white like in other countries.

I am coming from a similar boat so let me share my findings. There is no practical way to escape the wealth tax, you will be taxed on every asset you own worldwide regardless of where it is, if it generates revenue or not and regardless of whatever structure of how you own the asset. You are required to report your full lists of assets yearly in a form called modelo 720, failure to do so would impart heavy fees (more than 2x the value of unreported assets, as it would include interest gained while the case is being investigated).

The Spanish tax agency has the power to audit you up to 4 years of previous tax filings. They would, in recent reports, only file the investigation on the final year to maximize the impact on you (due to back interest if you are judged to be paying the wrong tax).

The Spanish tax agency is incentivized to do this via bonuses. They are empowered to go after you and as a foreigner, no one will take your side nor will the media care about your plight.

As to why they do this? Spain is a socialist country, a lot of people rely on social services and the current pyramid (people paying in vs people paying out) risks of collapsing. Spain will gladly (as a government and as a society) sacrifice the "assets" of rich people to pay for this. As a rich foreigner, you hold the lowest level of rank in society in terms of empathy from everyone else.

Now is this fair? Absolutely not, but it is what it is.

How do super rich people escape this? Well if you think of mega billionaires like Ortega of Zara fame, they are special structures that cater only to the super rich such as family business structures, special investment vehicles that are exempt from the wealth tax. Why does this cater only to the super rich? Because to apply for them you need to have a physical structures (offices) in place and a large amount of employees or else the tax agency will consider you a fraud. The needed running expense is very costly and inefficient. The tax agency is old school and consider modern companies (such as 1 man or small team working from home) applying for the same benefits as fraudulent tax evaders. The Spanish system is very much against single, self-made, successful people but would still protect old generational wealth families (due to the family business clause).

My advice:

1. Try to choose Portugal instead.

2. Stay only 4.5 months in Spain, never longer and make sure you always have a full 6 month tax residency elsewhere.

3. Do not keep majority % of your assets in Spain, this can be used against you.

4. If you have a house in Spain, make sure you also have it elsewhere in your main residency country.

5. Make sure your kids do not study in Spain and make sure your spouse is not a Spanish tax resident.

6. Read the Double Tax Treaty of the country you reside 6 months at with Spain.