You can expect to pay certain charges and fees for both options, with the investment route being the more expensive. At the same time, proving Bulgarian descent three generations back will definitely not be an easy task. There is no particular document that you will need to provide. The procedure is comprehensive and subjective to a certain extent. You will definitely need the assistance of experienced immigration consultant to assist you with such an application. With all that being said, if you urgently need EU (Bulgarian) citizenship, I would recommend the investment citizenship program. If you are not in a hurry and you rather want to find your roots and get citizenship as an added bonus, then you should go for citizenship by descent.
