Depending on the type of work you do, you may need to complete a W-9 tax form for several entities. The federal government may require you to send one if you hire an independent contractor. On the other hand, a client of yours could ask you to complete a W-9 if you are self-employed and have performed services for them. Financial institutions may give you a W-9 if they cancel some of your debt or you open a new banking or investment account. 

The purpose of the form is to share important tax information with various institutions. But the W-9 is just one type of tax form you may come across if you are self-employed or receive money for reasons other than employment. Knowing which forms you need and how to complete them can make tax preparation easier.