In watching the testimony during the Manafort case, the prosecution seems to be attempting to make the case that Mr. Manafort defrauded banks by calling his rental property as a second home?
If you rent out your beach house 1 day a year, on your tax return you have to allocate your expenses between Schedule A (home mortgage) and Schedule E (rental property) based upon usage.
For example let’s say that you rent out your beach house through AirBnB for 100 days per year and the rest of the year either you use it or its sits available for you to use. Is it a vacation home or a rental property. The IRS would view it as both and in fact vigorously make sure that you properly allocated as many deductions as you could to Schedule E (rental property expense) where deductions are limited.
Under Banking Regulations, the lines blur to some degree. Some lenders don’t want their purchasers to rent out the property at all. Others look to the primary intent, does the debtor intend to reside in this property periodically or to use it to make money. But generally, if you reside in it periodically after you get the loan, it should qualify as a second home.