IRS SS4 Form applications are used when acquiring EIN Numbers, also known as Employer Identification Numbers. These EIN Numbers are 9 digit numbers designated to businesses, estates, trusts and partnerships for use of tracking all financial transactions for that identity.
The most common method of processing these is SS4 Form Online Processing.
When applying for a business, estate or trust bank account and EIN Number will be required prior to opening said bank account, most often times the bank will require the physical SS4 Form which can be downloaded via the SS4 Online website as well.
Clearly there are many reasons why you may apply for an EIN, in most cases people are generally looking for an SS4 Online when attempting to open new business bank accounts for a new business and they realize that an EIN is required with their businesses articles of incorporation in order to open their bank account.
Failure to follow the Internal Revenue Service guidelines for EIN Numbers and taxation in the USA can be punishable by fines and/or prison time so be sure to obtain your SS4 Online and properly file your taxes annually.