1% Rule on off market Duplex Deal

[Russ Marlborough]

I am currently running numbers on an off market deal for a duplex in my area. I am using the one percent rule but would like some clarification on when I should run the calculation. Does the 1% or 2% Rule come into play before subtracting operating expenses from monthly income or after? It seems obvious to me that it is after subtracting expenses but I would just like to confirm. Thank you in advance for your reading this and your help.