Regarding the Portugal's RBI program (aka the Golden Visa program), there are three possible types of investment: a transfer of capital, real estate acquisition and job creation. The documents you need to provide vary with the type of investment you want to do.
What documents do I need to provide if I apply for Portugal’s RBI program through a capital transfer?
I want to apply for Portugal’s RBI program by transferring the required amount of capital to a Portuguese account. Regarding the source of the capital and the fulfillment of tax liabilities, what documents do I need to provide?