There are two major types of trust: revocable and irrevocable. A revocable trust is a trust that can have its conditions changed after it’s been formed. A grantor may decide that the trust is going to be dissolved, or may make changes to the beneficiaries and the amounts give. An irrevocable trust is a trust that cannot have its conditions changed (unless all parties involved agree to modify or dissolve it). A grantor cannot take this type of trust away from the beneficiary.
A revocable trust doesn’t need a tax ID or EIN, because it’s still under control of the grantor. But an irrevocable trust will need a tax ID or EIN, because the irrevocable trust is formed as its own entity, and pays its own taxes and files its own tax returns. Irrevocable trusts are often formed after an individual’s death, and a revocable trust will become an irrevocable trust after the initial grantor passes on, because the grantor no longer has any control over it.