NPI, stands for national provider identifier.   CMS initiated this reform to simplify filing claims.   The rest of the carriers are being forced to follow suit.   The NPI will replace all numbers that you were previously using to file claims, i.e., your Medicare numbers, BC/BS numbers, etc.

The website NPPES (https://nppes.cms.hhs.gov?NPPES/Welcome.do) is where you go to create your login and password, and get your NPI number(s) issued.   If you enter your information incorrectly, you will get denied on every claim you submit.   The NPPES site has to match what your local intermediary has on file for you.   Your clearinghouse has to match everything in their electronic file to send to the local intermediary.
Article contributed by Ken Lee, PRS, Inc., a physiatry practice management company to include billing services, [email protected], 1-800-324-4777