27. If one obtains a property or capital fund, strictly speaking, he must set aside maaser for the face value once, and then again on any returns he gets.
28. Received an apartment. Thus, if one received an apartment as a gift or as an inheritance, officially he must give maaser for its value. However, he isn’t obligated to spend money from elsewhere as maaser (יוסף אומץ פ' הצדקה והמעשר, שו''ת שבט הלוי ח''ה סי' קל''ג ). If he rents out the apartment, he must set aside maaser from the rent money. If he sells the apartment, he must set aside maaser from the money he receives for it (שו''ת שארית שמחה סי' ל''א, כ''ק מרן גאב''ד ירושלים ).
29. Using rent income to pay off a mortgage. If one bought an apartment for, say, $300,000 as an investment and paid $100,000 himself, taking out a mortgage from the bank for the remaining $200,000, and he is paying off the mortgage with the rent money he is collecting, he does not need to take maaser off that money; it is considered an expense to pay off his mortgage. However, if he will sell the apartment, he will need to take off maaser for its principal value, i.e., the $200,000 that he did not yet set aside maaser for (כ''ק מרן גאב''ד ירושלים ).
