To figure out the amount you are eligible to contribute you first must subtract half of the self-employment taxes from the net business income then do the calculation.

So you take that and divide it by 4 ($121,087) then subtract your current entitlement used ($36,000) which equals $85,087. 

For a quick and dirty look I usually do 30% of rent plus debt/ins/tax and subtract that from expected rent to get cash flow.If they all come out close to each other on the positive cash flow side I’d get the 4 unit first.

Sell price: $400,000Historic Rent: $2000/monthMortgage: $1980/ month (30 year, 5% interest, 10% down)Expenses: $550/month (estimate including maintenance, ins, 10% vacancy, PMI, and taxes)Cash flow: approx -$682 Alternative deal analysisSell price: $375000 (subtracting 6% realtor fee)Rent: $2000Mortgage: $1333 (30 year, 2.5% int with 10% down)Expenses: $350 (same as above without PMI)Cash flow: approx $120This second option is not stunning necessarily, but perhaps there is more room to decrease the sell price and increase the margin.

Usually typically you start by subtracting a vacancy percentages from gross rents.

After that you will subtract  estimated repair costs that number you have there should be close to the value of the property you are analyzing 

Subtract the loan on my portion of 80K, and the value of the remainder is left at 18K.

Add/subtract ALL the numbers.You want to move on? 

Subtract the cost you incurred in buying, the cost of the rehab and maintenance and the cost in selling and you have very little profit....and with 2 units even if you did live it in for 2 years, you do not get to totally not pay taxes on the capitol gains as its a duplex.

It might also mean that they'd have to install a bigger transformer, and they want to subtract part of the cost of the new transformer from you.