Deprecation when analyzing deals

[Camren Ritchey]

Hello everyone,I am looking to purchase a duplex in Lewisburg, WV. It has 2 bedrooms 1.5 baths on each side. I am in negotiations about the purchase price of the duplex. I have been running the monthly cash flow using the Bigger Pockets rental calculator. The current owner has been sending me some of his owner numbers. My numbers are telling me it will negatively cash flow at the purchase price they want. His number are saying it will cash flow. He is including the deprecation of the property in his numbers which is around $7000 a year. I have never heard of including that in the monthly cash flow. I am new to this and am looking for some guidance. If anyone could point me in the right direction that would be great. Thank you in advance.