Quick answer

When you open probate in Illinois, you generally must provide written notice to all known heirs, beneficiaries (devisees/legatees), and certain interested parties, and you must publish a formal Notice to Creditors for unknown creditors and unknown heirs. Exact requirements depend on whether the estate is being opened informally or formally, whether there is a will, and whether heirs are known or unknown. The controlling law is the Illinois Probate Act (755 ILCS 5). For precise procedure, check the Probate Act and local court rules or consult an Illinois probate attorney.

Detailed answer — what notices are typically required in Illinois probate

Below is a practical breakdown of the common notices you will encounter when opening probate in Illinois. This describes the usual steps and the categories of people who must be notified. Always confirm the specific requirements in the statute and with the probate clerk in the county where you file.

1. Notice to known heirs and beneficiaries (personal service or mail)

When you file a petition to admit a will to probate or for appointment of an administrator, you must provide notice to the persons who are entitled to receive formal notice under the Probate Act — typically the decedent’s heirs-at-law, devisees named in a will, surviving spouse, and other interested persons named in the petition. This is to ensure they have an opportunity to appear and object.

How notice is given:

• Personal service or certified/registered mail with return receipt is commonly used for known heirs and beneficiaries when addresses are available.
• You must file proof of service or mailing with the court (an affidavit of service or a return receipt).

2. Citation or court-issued notice of hearing

When the court schedules a hearing on a petition to admit a will or appoint an administrator, the clerk or the petitioner will cause a citation or notice to be served on interested persons. That citation notifies them of the date and time of the hearing and the nature of the petition. The Probate Act sets out who qualifies as an “interested person” for purposes of citation.

3. Notice to creditors (published Notice to Creditors)

Illinois requires publication of a Notice to Creditors to give unknown creditors and unknown heirs public notice that an estate is open. The Notice to Creditors must be published in a newspaper of general circulation in the county where probate is filed. The published notice starts the statutory period within which unknown creditors must bring claims.

Publication details (what is typically required):

• Place notice in a local newspaper (the county’s paper of general circulation).
• Publish for the number of issues required by the court or statute (counties commonly require weekly publication for several weeks).
• File an affidavit of publication with the court after publication runs.

4. Notice to known creditors

In addition to publication, a good practice (and sometimes a requirement) is to mail written notice to known creditors whose identities and addresses are available. Mail sent to known creditors provides stronger protection and can shorten disputes later.

5. Notice to minors, disabled persons, and guardians

If an heir or beneficiary is a minor or legally incapacitated, the court may require that a guardian ad litem be appointed and served. The guardian ad litem protects the interests of that person during proceedings. The petitioner must identify minors or incapacitated persons in the petition and follow the court’s instructions for service and appointment.

6. When addresses are unknown — constructive notice by publication

If you cannot find an heir’s or beneficiary’s address after reasonable diligence, the court will usually allow notice by publication. The published notice should meet the statutory requirements and you must document your attempts to locate the person (e.g., searches, contact with relatives, online searches) to show the court you exercised reasonable effort.

7. Filing proof of notice

After serving or publishing notices, you must file proof with the probate court:

• Affidavits of service or mailed receipts for personal/mailed notices.
• Affidavit of publication from the newspaper for published notices.
• Copies of the notices and any return receipts or signed acknowledgements.

8. Statutory authority and where to check the rules

The Illinois Probate Act governs probate notices and procedures. See the Probate Act (755 ILCS 5) for the statutory framework and specific section references. Your county court may also have local rules that affect timing, the format of notices, and publication procedures. The Illinois General Assembly’s page for the Probate Act is here: 755 ILCS 5 — Illinois Probate Act.

Because notice requirements vary by situation (will vs. intestate, formal vs. informal administration, known vs. unknown heirs), review the Probate Act sections and ask the county probate clerk for the local checklist.

Practical step-by-step checklist

1. Prepare the probate petition and list all known heirs, devisees, beneficiaries, and creditors with addresses if available.
2. File the petition with the county probate court and obtain the case number and hearing date.
3. Serve personal notices (or mail via certified/registered mail) to all known heirs and beneficiaries. Keep proof of service.
4. Arrange publication of a Notice to Creditors in the newspaper of general circulation if required. Obtain and file the affidavit of publication.
5. Mail or personally serve notice on known creditors, spouse, and any parties entitled to special notice (e.g., named executors or administrators not petitioning).
6. If heirs or beneficiaries are minors or incapacitated, request appointment of a guardian ad litem and follow court directives for service.
7. File all proofs of service and publication with the court before or at the hearing, as required.

Helpful hints

• Start by creating a thorough list of likely heirs: spouse, children, parents, siblings, and their descendants. Errors in the heir list cause delays and challenges.
• Use certified mail with return receipt, or a process server, for personal service when possible. Keep copies of everything you mail or serve.
• Document your attempts to locate missing heirs (calls, emails, social media checks, posted notices). Courts want evidence of reasonable diligence before allowing publication-only notice.
• Check the county probate clerk’s website or call the clerk for local publication requirements (which newspaper is acceptable, how many issues, etc.).
• File affidavits of service and proof of publication promptly — missing or late filings can invalidate notice and delay probate.
• If you identify creditors or heirs after publication, promptly provide them with notice and consider how late claims will be handled under the Probate Act.
• Consider consulting a probate attorney early. Probate rules and timelines can be technical and mistakes in notice can create personal liability for a personal representative.

Where to read the law and get court-specific guidance

Start with the Illinois Probate Act: 755 ILCS 5 — Illinois Probate Act. For county-specific publication rules and local procedures, contact the probate division of the county circuit court where you will file.