My dad just died of cancer and his 401(k) somehow only has $20,000 left in it. His employer is claiming he withdrew a big chunk. What can I do?

Let’s pretend, for example, that Carlos’ father died from cancer, and Carlos is trying to help out his mother who doesn’t speak much English. The problem is that Carlos has discovered his dad’s 401(k) only has $20,000 in it when he was expecting the balance to be much larger.

Carlos is trying to sort out where the money went, but he’s not sure how to solve the mystery. Here’s what he needs to know.

The plan administrator is the first place to turn

Fortunately, Carlos may have some tools at his disposal to try to find the money he believes should be in his dad’s 401(k).

“The first step would be contacting the plan administrator of his 401(k) plan to ask your question and see what information the plan would need to release the information,” Lisa Gomez, former head of the Employee Benefits Security Administration (EBSA), a federal agency responsible for protecting job-based retirement & health benefits, told Moneywise.

“Generally, the person requesting would need to have legal authority over the plan participant’s estate, such as an executor or other legal representative,” Gomez explained. “The plan is required to provide a statement showing the account balance and information about distributions that have been made.”

Gomez explained that the spouse or designated beneficiary on the plan would also potentially have the authority to request this information, and said there are options if the plan administration doesn’t provide it voluntarily.

“If there’s any problem in getting information or determining next steps, the federal agency that oversees 401(k) plans is the Department of Labor’s Employee Benefits Security Administration. Their benefits advisors are wonderful in assisting if you run into problems,” Gomez said.

Information from the plan may be more limited than Carlos would prefer

While Carlos should be able to get hold of 401(k) plan statements, this may not provide him with the information he’s looking for.

“Federal law gives a beneficiary the same information rights the participant had,” Aaron Hall, a business attorney in Minnesota, told Moneywise. “The plan administrator has to hand over the plan document, the summary plan description, the plan’s latest annual report, and a statement of the account.”

While Hall explained there are penalties for plan administrators who don’t turn over the requested records, “what the law does not require is a forensic trace, and that distinction is where families get frustrated. The plan owes you its records and its rules, not proof of where money went that left the account years ago.”

Additional detective work may be required

Fortunately, the plan documents may give Carlos and his family a good starting point for where to look to try to find any missing money. He just needs to do some detective work to see what he can find.

Hall recommended that Carlos start by reading his father’s tax return. “Money that came out of the 401(k) while he was alive generated a Form 1099-R, so his returns and his own files often answer the question faster than the plan does,” Hall said.

Hall also recommended that Carlos “look for accounts nobody knew about” because “money a family believes is missing from one 401(k) is frequently sitting in a plan at a former employer or in an old rollover IRA.”