buying 2nd apartment in the same building

No, unless you own the entire building, in which case you can fudge the proportion of total building expenses that are allocated to your investment property, so you can play with the accounting of income & expenses for the investment property. Otherwise, you are taxed based on the individual unit's assessed value (condo), or the unit's allocated # of shares (co-op).

...renovice yes there are tax benefits. Don't know your situation but you can deduct up to 25k for each investment property against your ordinary income. Simply your accountant takes revenue(rent) and deducts expenses(depreciation, operating, tax, interest etc) . Treats it like a business. Smart move but word of caution: your focus is cashflow and cashflow means a timely paying tenant. Find yourself a good tenant and you're set.

^^ they're tax benefits that only apply if your income is below a certain threshhold; OP check with your accountant, because you may make too much money to be able to take those deductions.

ali r.
{downtown broker}

I think the OP is more wondering if the is an additional tax benefit to having your investment property in the same building, as opposed to somewhere else. I'd like to know too but can't imagine there would be unless its the situation Aaron2 describes.