Company
Assuming you purchase the property through a company, once the company is registered in the commercial register, there will be a need to prepare year-end financial statements and corporate tax return, a real estate tax report, and filing with the financial office and commercial court.
EU Card
Assuming you purchase the property as a private person, you will be required to submit a real-estate tax return, and for properties that are let, you will additionally be required to register for income tax and prepare and submit a tax return showing details of income and expenses.