How does the executor pay off debts and final expenses if all accounts have beneficiaries names?

I'm afraid that if your mother's accounts are POD, payable on death, with the siblings listed as equal beneficiaries, then the money may go straight to the siblings without going through probate. Is anyone listed as co-owner with right of survivorship on any of those accounts? I ask this because, my mother died back in October and years before she made me joint owner of her various accounts with right of survivorship. Those accounts did not go through probate.

I was advised to do exactly as CarolLynn described. I am POA for my mom, so although most accounts have a POD listed, I keep one savings account with enough to pay funeral expenses, inheritance taxes and other debts without a POA. I have been advised that in my state, if there is less than $100,000 of "undesignated" funds at the time of death, we can do an informal probate (which is very inexpensive relative to a full, formal probate). This way, there will be money available without the need to collect part of it from my uncooperative brother.

You go through probate. Get a lawyer to help you, there are many pitfalls.

HolyCow, I assume that you are your mother's Durable POA. I would find out more details about the Trust to see if there is a beneficiary listed. Her money should be being used for her care which includes groceries and other bills plus a nursing home if and when needed. Medicaid would come into play at the point of a nursing home if she does not have any money left to pay for it. I find myself a bit confused when you say that the house is paid for in full, but then say that you pay her rent. Does that mean you are paying her rent because you are staying with her. You are taking care of her 24/7 and I don't see any reason why you would pay her rent for living in the same house with her. I think you need to protect your own money which you will need one day and go ahead and spend down her money on her care and keep good records when you do.

I read the original post again and noticed the POD this time, so probate is not necessary. That will save some money and time. No estate account will be needed. In a circumstance like this, does anyone know if the creditors are out of luck if the beneficiaries choose not to honor the debt?

You state that you expect to be the executor of an estate and there are insufficient funds to pay all creditors because there are beneficiaries listed on the accounts, hence the accounts are not subject to probate.
What happened in your case is actually the result of proper planning. By designating beneficiaries of each account, they avoid probate.
However, if you act as executor, you will have a personal responsibility to administer the estate properly. That is to say, if it is not done correctly, then you must pay from your personal funds. Therefore it might be a good idea to either get insurance, or retain an attorney who is licensed and insured.
Legal fees and expenses of administration are first priority claim, so it is paid before all others. In Pennsylvania, my state, the priority of claims is set forth in Section 3392 of Title 20 of our laws. Section 3162 of the Code provides that the executor must advertise the grant of letters and notify creditors to bring claims within one year. Also, although the accounts with beneficiaries passed outside probate, there may be Inheritance taxes due on them. It depends upon the state laws where you live. There may also be Medicaid claims due against the estate. As you can see, it can get complicated, but only for someone who has not done it many times before. I hope this information helps.

HolyCow, thank you for taking the time to answer. Your answer demonstrates the difficulty of communicating across state lines.You see, probate laws are governed by the states rather than federal law, and each state has their own set of laws.
There are differences: For example in my state, Pennsylvania, you do not file a Notice to Debtors and Creditors and wait 120 days. Rather, you publish a notice in the local paper and the creditors must respond within one year (with some minor exceptions). In my state, Pennsylvania, there is an Inheritance Tax due on every estate, no matter what the value. As you point out in your answer, there is also a Federal Estate Tax for large estates over $5.M, but "Inheritance Taxes" are different from the Federal Estate Tax. Every state has their own law about Inheritance Taxes.
Many of us who practice Estate Planning and Elder Law know Ed S. (nice guy) and about trust to trust transfers of IRA accounts (which were used before Ed came along and marketed them). We frequently set up trusts for protection of beneficiaries to protect against Medicaid claims and more. However, the law directs that you do it at least five years in advance. If you do, it is perfectly legal.
If you have a state specific question about law, I suggest avvo.com where you will get a free answer from a local lawyer, about your state's laws. I think this forum is great for ideas for caregivers, but not the place to post legal questions, because there are 50 different sets of laws, and an answer may be incorrect and harm someone. I also answer questions on Avvo. I will continue to use this site for helpful information about caregiving, but it's not the place for legal questions if there is a much better alternative, more likely to provide the correct answer.

If there is more than $75,000, then you will go through probate. Before her death, get an irrevocable trust drawn up stipulating debts are paid first before beneficiaries. There were five of us, and that is what my sister did.

I am concerned by looking through the above answers to your question that you are receiving "advice" from folks who are not associated with the legal system and are not clear on probate law. I am only a paralegal but have worked in probate for over 30 years. I don't know any attorney who would advise that all of our mother's funds be held in TOD or joint accounts. There needs to be an account from which her final expenses are paid. In addition, if she owns a home that will be put up for sale, there should be enough money available to continue to pay homeowner's insurance, utilities, and the mortgage payment until the home can be sold. A will governs both the distribution of real and personal property in accordance with your mother's wishes. It is true that a small estate (varies in value from state to state) can be handled without filing a formal probate, but there will still be expenses and your mother's assets still have to be distributed according to her Will, if she has one. I would suggest that you contact an attorney of your mother's choosing for advice. If your mother does not have the capacity to do so and you have a Power of Attorney, I would suggest that you set up an account to prepare for paying off expenses. A predisposed plan to have all funds in TOD and joint accounts to avoid paying expenses could present problems as a creditor is able to file a petition for probate or can file a claim in any probate you file. If intentional avoidance of paying the decedent's expenses is proven, the beneficiaries could potentially have liability for claims against the estate.

theresa are these accounts POD "payable upon death"? If so, then the money goes directly to the people listed as POD. Are these beneficiaries listed as POD on her accounts?

My mother made me joint owner with right of survivorship of all her personal accounts. Upon her death, the accounts became mine and I paid her final bills from those accounts. Thus, there was no need to set up an account called the estate of ____ from which the person's final bills are paid.