Every business must have a CRA Business Number. This is the 9 digit standard identifier for your business. This is applicable for a federal or provincial corporation, or a sole proprietorship or a master business license or a trade name or a partnership). However, a separate business number is not required, if you are registering;
A master business license or trade name under an existing corporation that already has a business number, or,
A sole proprietorship and you already have business number assigned by CRA.
GST/HST Account (RT)
Every business that operates and collects GST/HST, MUST have a registered GST/HST account with CRA. The payment receipt or invoice must show this number. A GST/HST account number is used not only to collect GST/HST from customers, but it is commonly used claim the return of the GST/HST amount that you have paid for buying things or furniture or equipment for your business.
Corporate Tax Account (RC)
A corporation must have a Corporate Tax ID regardless even though its income is zero. This account, as if the SIN number for the corporation, used to file the corporate tax return with CRA. It is REQUIRED for a corporation only, not for a sole proprietorship or master business license or trade name or partnership.
Payroll Account (RP)
Once you know that you are an employer, trustee or payer, you NEED to open a payroll account. You can claim for employee expenses. Not only an outsider, but the business owner himself or his family member could be considered as an employee if the payment is done through a payroll account.
Import Export Account (RM)
If your business imports goods into Canada or exports goods to other countries, you NEED to register for an import-export account. CRA will use this account number to process customs documents. To avoid delays in releasing your goods at the border, you must open this account before you import or export goods.