Q: My parents created a trust several years ago and my dad has since died. Can my mom amend the trust on her own?
A: Maybe, but it's going to be determined by the terms of the trust.
Trusts are obviously legally enforceable documents. Since they are legal documents, you should first look at the terms to determine how they operate. The trust should set out if and how it can be amended and under what circumstances.
The most common types of trust are revocable and amendable, so my gut tells me that it's likely the trust can be amended. The wrinkle in your situation is that one of the Settlors, your father, has passed away. Because of that, I'm somewhat less certain that the trust can be amended by the surviving Settlor and, without actually reviewing the document, there is no way for me to know for sure. However, if I had to venture a guess, I'd still guess that she could amend it on her own.
Joint revocable trusts are usually written pretty broadly and anticipate changes. If the trust was going to become irrevocable after a death, chances are each of your parents would have had their own trust agreement. Also, in order to maintain certain protections granted to real estate owned by husband and wives, ownership after the death of one of the spouses needs to exist. It's difficult to retain those protections if the property is owned by an irrevocable trust. I guess what I'm saying is that I can't promise it, but it has been my experience that joint trusts are usually amendable even after the death of one of the Settlors.
Now some attorneys try to set limits on the ability to amend the trust by restricting what can be changed. For example, the trust may be amendable after the first death except for changing the residuary beneficiaries. In other words, the surviving Settlor can amend anything in the trust except for who ultimately gets the money. However, provisions like that are usually just smoke and mirrors because if the surviving Settlor can amend the trust, chances are he or she can take all of the assets out of the trust and create a new one thus getting around the restrictions.
If your mom wants to amend the trust, I suggest that she make an appointment with the attorney who drafted the document and discuss the changes. She will at least find out if changes are allowed or even necessary.