If you plan to refinance rental property, there are certain IRS tax rules you should know. 

Sec. 162(a) specifies that trade or business expenses only include ordinary and necessary expenses paid or incurred during the taxable year in carrying on any trade or business.

If a rental is refinanced, the equity debt portion of the loan, unless used to make improvements on the rental, would not be an ordinary and necessary business expense. Thus, equity debt on the rental does not meet the requirements of Sec. 162(a).

Also, a personal interest deduction is specifically disallowed under Sec. 163(h).

If it were not this way, an individual could borrow money against the rental for personal things like vacations, cars, boats, etc., and be able to deduct what would otherwise be non-deductible personal interest.