Does jointly owned property have to pass through probate?

The answer depends on who actually owns the property and how you hold title to it.

Ownership. If your father is just a cosigner on the mortgage—not a co-owner of the property—then his death would not affect your ownership of the property. You would continue to be the sole owner.

Title. If you and your dad will own the property together, you can arrange your ownership so that no probate will be necessary when he dies.  The way to do that, in most states, is to hold the property as “joint tenants with right of survivorship.”

If you buy the house together, and the deed that transfers ownership to you states that you own the property as joint tenants, then ownership of the property would automatically pass to you at your father’s death. Probate court proceedings would not be necessary; you would probably just need to record (file) a death certificate in the county land records office. (The paperwork that’s required varies from state to state.)

It’s important to realize that every state has its own rules about which words you must use to establish the right of survivorship for a surviving co-owner. Look up your state’s rules (a law librarian should be able to help you) or ask a local real estate or estate planning attorney.