Why do I have to let my ex-wife (ex-husband) know that I’m filing for bankruptcy (dso)?

Because it’s the law.

That being said, you only need to list them if they are a co-debtor on something you’re listing in the bk or if you owe them a domestic support obligation (dso) like child support or alimony?

What if they’re a co-debtor?

Well, if they are a co-debtor, it means that they are also liable on the loan you are wiping out in your bankruptcy. Let’s say you both took out a car loan 2 years back, and you were supposed to pay for the car after your divorce. Unfortunately, you did not, and the car was repossessed. When you file bankruptcy, you can discharge those repo fees, but they will come after your ex for the balance. You need to let him/her know what’s happening. Even if you don’t like them, it’s the least you can do.

What if you pay them child support or alimony?

You are required to list them as a creditor in your bankruptcy, and the trustee will require you to fill out a Domestic Support Obligation form. Here in Utah, we use variants of this form: the Domestic Support Obligation Questionnaire.

The simple reason for you to fill out this DSO form is because the bankruptcy trustee needs that information to contact your ex-spouse directly. He/she is required to send two notices to your ex, the first one saying that they still have rights to receive DSO payments, and the second to say that there was a discharge of your other debts.

I am linking sample letters from the US Trustee’s Office (Department of Justice) that the trustee sends out here:
https://www.justice.gov/ust/file/478681/download .

I receive phone calls from ex-spouses of my clients wondering why they are listed in the bankruptcy case and how this will affect them. I hope that I put their minds at ease when I tell them that they will keep receiving their child support payments. We are discharging the other debts, not the domestic support obligations.