After setting up a revocable living trust, clients sometimes run into problems with bankers, stock brokers or even accountants telling them they need a separate tax ID number for their revocable trust. Usually, this is not the case. A revocable trust uses the social security number of the person who created the trust and still holds the power to revoke the trust. As long as the trust remains revocable (and has not become irrevocable or partially irrevocable because of the death of one or more persons setting up the trust) the creator of the trust can continue to use their social security number just as they did when they owned the assets individually. Any income generated by trust assets is reported on the tax return of the trust creator holding the power to revoke.
A trust may start out as a revocable trust but later become an irrevocable trust. This most commonly occurs when the creator of the trust dies. When a married couple creates a joint trust, the trust may become irrevocable or partially irrevocable when one spouse dies, even if the other spouse is still living. Any irrevocable or partially irrevocable trust must have its own tax ID number (EIN). If the trust generates sufficient income, the trustee will need to file separate trust income tax returns as long as the trust continues to exist.
A trust never needs to use the social security number of the trustee, unless the trustee is also the creator holding the power to revoke the trust. If the trustee changes, you would continue to use the social security number of the creator holding the power to revoke (if there is one), or the tax ID number for an irrevocable trust.