If you need at least one of the four CRA business accounts (RT, RP, RC or RM), you will need a BN.
However, before you register for the BN, you need to know a few things about the business you plan to operate. For instance, you should know the name of the business, its location, its legal structure (sole proprietorship, partnership, or corporation), and its fiscal year-end. You should also have some idea of what the sales of your business will be. Without this information, you will not be able to complete Form RC1, Request for Business Number (BN).
Note
If you are a sole proprietor or a partner in a partnership, you will continue to use your social insurance number (SIN) to file your individual income tax and benefit return, even though you may have a BN for your GST/HST, payroll deductions, and import/export accounts.