Dad doesn’t have assets. Does he need a will?

If your Dad is on Medicaid, is it possible Medicaid might claim that money? If there's more in that account than is allowed by Medicaid, how is that happening? My MIL is on Medicaid. After 3 years she never has had more than $350 in that checking acct after the NH withdraws its payment. Does you Dad have a Resident Trust at his facility? Medicaid can't touch that money, but there is a limit to how much can be in there. Also, does your Dad have a pre-paid funeral? If not, I'd put it towards that (Medicaid allows approx. $1500 for cremation).

If it's any type of financial account, the easiest thing would be to add beneficiaries. That would avoid probate.

Doublecheck with a banker if you have your father add you and your siblings on a checking account.      There's precise wording that bankers use when creating a POD account, and they'll advise you of that.

If he writes a "note", it might be considered a holographic will, as Mountain Moose suggests.     But if he has no assets, there's nothing to probate, and, ergo, no need for a will.  

However, there is the house.  Does your father own it?    I'm assuming though that you're anticipating no value left in the home in which he's living (per your profile), car, or furnishings your parents had after Medicaid recoups its advances?

It seems the house would be the only asset to dispose after he passes.  How is it titled?  Specifically, as in your father's name only?  The 3 children aren't identified as heirs?  

Is he still competent? If so, have him instruct the bank to make the checking account a Payable on Death Account (POD). It will keep any funds in the account out of the probate system, and will allow you to use the funds immediately after his death to settle final things like funeral costs out of his funds.

I agree with DollyMe about putting you and your siblings on his checking account as beneficiary (you may need a death certificate to give to the bank), or be added as a secondary owner so you could use his checking account on his behalf now.

There's nothing wrong with having a will. Can't hurt, might help type of thing.

He (or you) can download a free template and follow his state's laws for witness or notarizing requirements. If the Internet or a computer isn't easy to get to, there's always the library to access, download, draft, and print.

He can also write out a holographic will, which is entirely handwritten and he may have to have it witnessed (check with his state laws for requirements).

I see from your profile he has dementia / Alzheimer's. Ensure any actions are signed by him when he is competent to know what he's signing.

All he needs to do is add the children as a beneficiary to his checking account. He does not need a will if he has nothing.