For a private person it is 19%. Costs of redecoration (painting, new tiles, kitchen and other furniture), agency and legal fees can be offset. You can also offset value-increasing renovations (expansion, new heating system) from the profit for a private person. Make sure you keep the invoices and bills.
No capital gains tax after 5 years if ownership for private persons. If you have your residence registered in the apartment, you do not have to pay capital gains tax after 2 years.
For a company the corporate tax on profits is 19%. The advantage here is related expenses and utility costs can all be offset against income.