We had to get certifications for a few things and fix up here and there.

The fact that you usually pay for the property in an auction Before this happens I believe is irrelevant.Hers it’s a 15 day lag between paying for the auction and the deed (certificate of title) being executed.

The codes inspector told me he could not issue me a permit because the house had not been issued a CO (certificate of use and occupancy) as it was a brand new house that I was building.

First time was the annual inspection second time was some kind of certification. 

I am well versed with the FHA 203k Rehab Loan for all areas of the country because of my role as the Director for the National 203k Contractor Certification Program. 

Review the leases and if you get it under contract get an estoppel certificate from the tenants before closing.

STRs here in Santa Fe require certification.

Also known as Tenant Estoppel Certificates.

I've Googled it and the state of Colorado does not require contractors to pass an exam or receive a certification to operate a business as a contractor so where would I go to learn?

Some States do tax sale certificates (pretty new) or tax deeds (been around ).