My understand is that commercial real estate loans require additional collateral for lower rents than what was agreed to when the mortgage was created. Building

My understand is that commercial real estate loans require additional collateral for lower rents than what was agreed to when the mortgage was created. Building value is basically (monthly rent * constant).Accepting lower than when the mortgage was written will trigger provisions that value the property differently and require the building owner to add principal to get back to 25%. If lowering the rent by 10k a year lowers the value of the building by 100k, the building owner may have to add 25k that they don't have to keep the building from falling into default. If you have a completely empty building and you accept a lower rent in one of ten units, you could need to put down 250k it of you have many building under one loan they may want millions because of how it changes the loan valuations.