However your longest time frame you have imagined to get it ready to move into, multiply that by 3.And you'll have driveways and sidewalks and landscaping to put in, which is enormously expensive, too.And in the meantime, you're paying rent somewhere else.  

Don't allow damage or graffiti or it will multiply.

I have yet to see a section 8 tenant that could qualify.There has been case law where tenants prevailed on the rent multiplier requirement by Sec 8 landlords.  

And even a high multiplier is no guarantee that the tenant can afford the place.

Although it is later aggregated and then multiplied by the business percentage, the IRS could easily multiply line 18 by the business percentage to calculate the amount that would be reported on Form 1099.  

@jamesTo expand on what @Linda Weygant said about the home office deduction no longer being an audit flag, the IRS now allows a "simplified" method where you simply multiply the square footage of the office by $5 and that's your deduction.One has to think that if the IRS is offering and encouraging a simplified method of reporting, it's not going to be the cause of an audit.

It's a multiplier value of almost any other market out there, or in % speak that is to say 200%, 300%+ MORE available rental inventory for tenant's vs other markets.   

That should multiply your income when second unit is rented.

Think,, if you can put down 10%,15%,20%, that means you can multiply your portfolio, and cash-flow with the same amount of money.If you haven't seen @Brandon Turner's webinar about "How to Invest In Real Estate With Other People’s Money" you should.

I have also seen appraisers use a calculation based on the unit's rents and the area's average gross rent multiplier as a supplement to the comps.