In the UK, for buy-to-let mortgages, lenders typically require projected rent to be at least ~140% of buy-to-let mortgage interest repayments. Moreover they rev

In the UK, for buy-to-let mortgages, lenders typically require projected rent to be at least ~140% of buy-to-let mortgage interest repayments. Moreover they review the situation regularly and require the landlord to pay off some or all of the principal if they are no longer eligible by that criteria. As a landlord, therefore, you will not be loaned the money unless there is profit to be made on the rent; we don't have to speculate - we know absolutely for certain that (rent-maintenance) is enough to pay off all the interest and a little principal each month, otherwise the bank would not have lent the landlord the money. I am rather less familiar with the US buy-to-rent mortgage market, but I understand there are similar eligibility criteria involved there as well.