To be an approvable builder, the builder must be a licensed GC in the state where the property is being built. They must have “happy homeowners” for references, presumably based on jobs similar in scope to the new construction project for which they seek approval. Vendor and bank references are sometimes required as well. A credit check is usually done. IRS liens are one area of concern, since the construction lender doesn’t want the IRS seizing bank accounts and stopping the project. The builder should have performed the previous work for their own company, not as the superintendent or employee of someone else’s company. If a builder cannot be approved, most homeowners would not want to use them anyway.