Dear Iris

Sorry for the late reply.

I'm quoting below the answer provided by Juan Carretero from Lawbird.

Wealth tax levies the worlwide assets. The first €700.000 are exempt from tax and €300,000 can be deducted from the valuation of the family home before it is added to the total asset calculation.

In your case, it would be €1,250,000/2 = €625,000 for each of you. Since you are below the €700,000 threshold, there is no need to file a wealth tax declaration. However if you are a Spanish fiscal resident and have goods and assets in another country worth over €50,000, you must file Form 720.
Kind regards