Can I challenge my sibling’s use of our deceased parent’s bank account for mortgage payments before a personal representative is appointed?

Short answer: Yes — but your options and the speed at which you can act depend on (1) how the account is titled (individual, joint, or payable-on-death), (2) whether your sibling has legal authority to use the funds, and (3) how quickly you can get the probate court to intervene. Under Arizona law, money belonging to a decedent that is not jointly owned or otherwise payable to someone on death generally becomes estate property. You can ask the bank to freeze the account, petition the probate court for appointment of a personal representative or a temporary (emergency) administrator, and pursue civil remedies if a sibling wrongfully takes estate funds.

Disclaimer

This article explains Arizona probate concepts for education only. It is not legal advice. For advice about your situation, contact a licensed Arizona attorney.

Detailed answer: what Arizona law says and practical steps

1. Who legally owns the money right now?

Under Arizona law, ownership depends on how the bank account is titled:

If the account was in the deceased parent’s name alone, the funds are estate property and generally must be collected and distributed by a personal representative during probate.
If the account was titled as a joint account with right of survivorship, or included a payable-on-death (POD) or transfer-on-death (TOD) beneficiary, the surviving joint owner or beneficiary usually becomes the owner automatically and the funds bypass probate.
If the sibling was an authorized signer but not a joint owner or beneficiary, they may access the account under the bank’s policies, but that does not give them legal title to the funds — and unauthorized withdrawals can create liability.

For an overview of Arizona probate law (Title 14, Arizona Revised Statutes), see the Arizona Legislature’s site: https://www.azleg.gov/arsDetail/?title=14. For practical court procedures and forms, see the Arizona Courts probate pages: https://www.azcourts.gov/probate and the Self-Service Probate resources: https://www.azcourts.gov/selfservice/Probate.

2. What can you do immediately (before anyone is appointed personal representative)?

Take these steps quickly to preserve estate property and document the situation:

Check the account title. Ask the bank whether the account is an individual account, a joint account, or a POD/TOD account.
Get records. Request recent bank statements and a transaction history. The bank or the sibling may resist, but a copy of the death certificate and a written request can sometimes release basic information.
Ask the bank to freeze disbursements if you reasonably believe the account is estate property and funds are being improperly removed. Banks often freeze accounts once they receive a death certificate, but banks also follow their own policies (and federal law).
Notify the mortgage lender. If mortgage payments are late or at risk, tell the lender that the owner died and someone is claiming to be using estate funds. Lenders may provide temporary forbearance or instructions about who to contact to avoid foreclosure.
Document everything. Keep copies of statements, messages, and any withdrawals made by your sibling.

3. Petition the probate court for a personal representative or temporary authority

If the account is estate property (not joint/POD), the best way to get legal authority to control estate assets is to open probate and have the court appoint a personal representative. In urgent cases you can ask the court for a temporary/emergency appointment to stop dissipation.

File a petition for appointment of a personal representative in the Superior Court in the county where the decedent lived. The Arizona Courts website lists local probate offices and forms: https://www.azcourts.gov/probate.
Ask the court for immediate relief. Courts can appoint a temporary or special administrator (sometimes called a temporary personal representative or emergency administrator) to protect assets while the full probate proceeds. That person can obtain possession of the bank account and make or stop mortgage payments as appropriate.
Once appointed, the personal representative has statutory duties to inventory estate assets, preserve property, and follow creditor procedures under Arizona’s probate statutes (Title 14). See general statute information: https://www.azleg.gov/arsDetail/?title=14.

4. Civil and criminal remedies if your sibling withdraws estate funds

Civil claims: If a sibling wrongfully takes estate property before a representative is appointed (or after appointment when they lack authority), the estate (through the personal representative) can sue for conversion, breach of fiduciary duty, or unjust enrichment. The court can order return of the funds plus interest and, in some cases, attorney fees.
Criminal charges: Willful theft of the decedent’s money could be a criminal matter. If you have strong evidence of theft, you can contact local law enforcement. Law enforcement evaluates evidence and decides whether to pursue charges.
Accounting and surcharge: After a personal representative is appointed, the representative can require an accounting and ask the court to surcharge (hold financially liable) anyone who improperly took estate assets.

5. Practical realities and timing

Probate filings and the court’s response time vary by county. If the account is clearly estate property and money is being taken, file for an emergency appointment immediately. If the sibling is the surviving joint owner or POD beneficiary, the court may have little or no power over those funds because they pass outside probate.

When to hire an attorney

Consider consulting a probate or litigation attorney in Arizona if:

Large sums are at risk or the mortgage is about to default.
The sibling refuses to provide account records or to return funds.
You need to file an emergency petition quickly to protect estate assets.

An attorney can prepare the probate petition, ask for temporary appointment, draft demand letters, and represent the estate in court actions to recover funds.

Helpful hints

Confirm account type first: joint and POD accounts usually pass outside probate.
Get a certified copy of the death certificate and any will — courts and banks will require them.
Request bank transaction histories in writing and keep all communications in writing.
Contact the mortgage lender and explain the situation to request temporary leniency if payments may miss a due date.
File for probate promptly if the account appears to be estate property — speed matters when funds are at risk.
If possible, gather other heirs and loved ones to reach an interim agreement in writing while the court acts; that can reduce conflict and delay.
Ask the court for emergency (temporary) appointment if immediate action is necessary to preserve assets.
If you suspect criminal activity, preserve evidence and consider contacting law enforcement in addition to filing civil probate petitions.

Where to find Arizona forms and statutes

Arizona Revised Statutes, Title 14 (Probate): https://www.azleg.gov/arsDetail/?title=14
Arizona Courts — Probate information and local court contact info: https://www.azcourts.gov/probate
Arizona Courts — Self-Service Probate resources and common forms: https://www.azcourts.gov/selfservice/Probate

If you want, provide the following (non-identifying) details and I can outline likely next filings and a short checklist to bring to the probate court or an attorney: (1) how the bank account is titled, (2) whether the decedent left a will, (3) whether your sibling is making payments from that account and when withdrawals started.