Second Conventional loans on a primary residence within a year

[Plaku Mere]

I have been buying and financing three 4 unit properties every 2 years taking out a primary residence conventional loan while living on one of the units. As I’ve been upgrading my living in bigger units each time. I just purchased a 3 unit property in February.

Yesterday say that my favorite house in the neighborhood came out on the market. Having made enough for a downpayment was thinking to apply for another conversational loan for a primary residence. I have heard that you need to be on your primary for at least 1 year before moving out ? Is this true ? Where is this rule coming from ? Freddy mac , Fannie Mae?