Asia-Pacific Economic Cooperation, or APEC, is the premier forum for facilitating economic growth, cooperation, trade and investment in the Asia-Pacific region.
Provider Transaction Access Number (PTAN) A PTAN is a Medicare-only number issued to providers by MACs upon enrollment to Medicare. When a MAC approves enrollment and issues an approval letter, the letter will contain the PTAN assigned to the provider.
DEFINITION of 'Transaction Authentication Number (TAN)' A one-time code used in the processing of online transactions. A transaction authorization number (TAN) represents an additional layer of security beyond a password to securely log into an account or conduct a transaction.