IF YOU'RE A REGISTERED BUSINESS, then your TIN was generated using your Corporate Affairs Commission (CAC) registration number.
INDIVIDUALS are required to enter their Date of Birth, BVN or phone number registered to their BVN.
BUSINESSES are required to enter their CAC registration number.
And just like that, you'd see your TIN.
After seeing your TIN, use the box beside the 'send email' button to send BOTH YOUR TIN AND YOUR TIN CERTIFICATE for safe keeping to the valid email address you will enter into that box. YES IT WORKS.
Hope this was helpful.
Be careful about where you print your TIN.