Is copyright registration mandatory?

No. So why bother? Registration provides you with an automatic presumption of copyright ownership and validity. It can be used to sell or license the copyright. Also if a legal dispute occurs, you do not need to prove ownership (a sealed self-addressed stamped envelope may not be enough) etc . . .

Your opponent has the heavy burden of proving that your copyright is invalid. During the legal dispute for instance, if you have a registration, your opponent cannot raise ignorance of your rights as a defence.

Furthermore, if any or part of your company’s success depends on its intellectual creativity capable of copyright protection, without a proper intellectual property protection strategy, your company’s existence may be short-lived. Lastly, independent research has shown that ownership of registered intellectual property significantly increases the market value of a company.