It is calculated as: the annual servicing fee divided by 365 multiplied by # days since last payment, then multiplied by the outstanding principal of the loan. (lendacademy.com)
These mortgages have an upfront fee that's included in the overall principal of the loan. (valuepenguin.com)
At the end of the 5 years, they would face a balloon payment with the entire principal of the loan. (bebusinessed.com)