On a 5,000 square foot suite at $16 NNN, a month of vacancy is about $6,700 of rent — but the real cost includes the operating expenses you now pay yourself, the utilities on an empty space, and the insurance surcharge many carriers apply once a commercial building has been unoccupied for 30 to 60 days.
That last one surprises owners every year. A standard commercial property policy contains a vacancy clause that suspends coverage for vandalism, glass and water damage once the building has been empty past the threshold. A vacant-property policy is a different product.