l mean to verify the existence of my business by a third party or by the customers, is it safe l give them my business number just so they could verify and confirm what l do. Have there been any frauds committed in the past with regards to business numbers.
yea biz tax number

If you mean your tax ID number, do not give it out. Confirmation should be evident in references from other clients, a place where you do business, how to talk and conduct yourself, etc.