The gift or sale of shares from you to your son will be treated as a disposal for Capital Gains Tax...
What is a Tax Clearance Certificate, and when might my business need one?
A Tax Clearance Certificate is a document from the Revenue Commissioners confirming that a business's tax affairs are in order. You may need this certificate when tendering for public sector contracts, seeking state grants, or if you're applying for certain licenses. It provides assurance to other entities that your business is tax compliant.