Repair of tangible personal property is taxable in many states, and also is prone to cash-based transactions.  Therefore, there is a significant risk of a cash economy and state sales tax not being collected.  Many online websites have appeared where consumers can look for reputable service providers such as AngiesList, HomeAdvisor or Craigslist.  These websites contain valuable information on business transaction activity that can be used as evidence when discovering unregistered businesses.  In a Northeastern US state, Harmari Taxcrawler was able to find a 30% unregistered rate on taxable service providers, which is a tremendous success at bringing more taxpayers into compliance.