When you lose a spouse, partner, or parent, the grief can be overwhelming. In the midst of that grief, life goes on. There are arrangements to be made, things to be taken care of—and in recognition of this reality, here is a checklist that you may find useful at such a time.

First, gather documents. Ask for help from other family members if you need it. Start by gathering the following.

—A will, a trust, or other estate documents. If none of these exist, you could face a longer legal process when settling the person’s estate. If a trust exists, consider contacting the professional or firm who helped set up the document.

—A life insurance policy. As a rule, you will need the death certificate, with the cause of death listed, to move forward with any claim.

—A Social Security card/number. Generally, the person’s Social Security number will be retired shortly following the death.

Then, gather these additional highly important items.

—Bank account, investment account, an...