The most important rule is to have the cash flow of the new property be able to pay all its expenses, mortgage, AND the line of credit back.

The "land basis" cannot be depreciated, so your depreciable portion will be lower than $350k.We typically consider $1 million in building basis as a rule of thumb where it makes sense to evaluate the potential benefits.

No, ok, rule in your favor.

So if I understand this correctly, by qualifying to extend the 5 year rule to 10 yrs, $250k if single or $500k if married of proceeds from this sale would be exempt from capital gains? 

Non conventional just means the loan will not be sold to Fannie/Freddie so they do not have to follow those rules.

I would put it in your listing details and also potentially house rules. 

I will not comment as to the tax laws and underlying rules - that is a discussion you can have with your tax advisor who presumably you are paying to help you.What I will do is provide practical and business guidance on tracking time.Firstly, there are apps available that can assist with time tracking where you can specifically detail your time, who you met with, etc.

@Polat CaglayanI've never seen a formula but here is a general rule of thumb for multifamily:The class of an apartment refers to the quality of the building, which can be determined by a number of factors, including age, location, and condition: Class A: These are the highest quality apartments, typically built within the last 15 years.

You’ll also want to have them sign a rental agreement that lays out your rules, payment terms, and any liability.

Don't focus on a "rule of thumb" as a rookie.