I use to be very inclined to do property tax certificates and deeds for sell by some states.  

City code inspector signed off in a flashall other units were as-is from date of certificate of occupancyOf course the buyer wanted changes and I sited:the property inspector is not a City code inspector and operating out side his authority.the upgrades past City code inspectionthe others were unmodified as installedThe buyer signed off and we closed as agreed.Unless the inspector works for the City Code Enforcement Dept, stand your ground.

What was needed was an engineered certification and/or affidavit of affixture (433a in Cali) which usually meant the need to install an engineered approved foundation under the home.

Unauthorized practice of contracting; impersonating contractor; false certificate; giving false evidence to Board; penalties, specifies violators of The Contractors law "shall be deemed guilty of a Class 2 misdemeanor."

So the apples to apples investment, where it's guaranteed ROI, would be a Certificate of Deposit, or Treasury Note, or similar, and those rarely offer more than your mortgage interest rate. 

Without looking at my docs, I don't recall the certification of occupancy having any term associated with it.

Buy a tax lien certificate from the county (or third party that already owned it long enough) and after statutory wait period go to tax deed. 

Full redemption value is the biggest motivator to me.We have some certificates in Maricopa County (AZ) at 16% if you looking to buy.

I did some looking online, are you referring to a certification that individuals can obtain?

For the electronics business I think I will need a tax certificate for buying parts wholesale and charging customers sales tax.