Jakerhod, some states require contractors to have a license. I would tell them a license is not required in your state. Maybe you can provide some other proof of your business like a bank statement, credit card bill, newspaper advertisement or yellow page listing. Plus, your tax returns should show them a history of your business. No matter whether you are a sole proprietor, partnership or a corporation, there is information about your business on all these returns. Good luck, hope everything goes smoothly!