If you have only 1 child (the son you write) that you want to include, then it is easier to have your child buy the property. Biological parents are included in the applications without age limit. The child can renew for one of the other categories (e.g. work), but he needs to stay in Greece at least 6 months per year.
How could dependents keep status in the Greek Golden Visa program when they age out?
I want to invest 250,000 euros in residential real estate and apply for Greek Golden Visa program. My son is currently 20 years old. When he reaches 21 years old, does he have to invest in the program and own a property of his own to keep his status?
The Greek immigration authorities grant the Golden Visa to dependent children up to the age of 21 years old, however, they accept that the investors' children to retain their residency rights by switching to another type of residency for three more years up to the age of 24. After that, the investors' children should find their own reason for residency (for example, buy a property on their own) Therefore, before the expiration of the Golden Visa, he would be required to switch to the other type of residency up to the age of 24. We usually recommend applicants with one child older than 18 years old to buy the property directly under their child's name, so the parents will qualify as dependent members of their child (who will be considered the main investor).
According to the Greek Immigration Law in force, children of third-country nationals, who have been admitted to Greece under the terms and requirements of a residence permit for property owners, are granted a residence permit for family reunification until the age of 21. After that, it is possible to acquire a renewal as a 3-year independent residence permit until they reach the age of 24 and then it is possible to renew it further according to pertinent immigration legislation. However, we could propose to consider the possibility the potential investment to be implemented on behalf of your son, given that under the current legal framework, the investor's parents are entitled to acquire the permanent residence permit too.
If your son gets the residency card based on your investment before he turns into 21, then he will be entitled to extend his residency permit until the age of 24. After the age of 24, he will have to renew his residency card on a different basis, i.e., a work residence permit, studies residence permit, etc. There are several types of residency permits in Greece and it is highly likely that he can fit in one of them. If he does not get the residency permit based on your investment before he turns 21, then he will have to make his own investment or find another way to get a residency permit.