Written by Acorn Sales Company, manufacturing stamps and seals since 1964 · Reviewed by Holly R, VP of Sales and Marketing at Acorn Sales, against the Illinois State Board of Professional Engineers, which advises the Illinois Department of Financial and Professional Regulation and 225 ILCS 325/15(a) and (c) on 21 September 2026 · Updated 21 September 2026
Illinois asks for an expiring date on the face of sealed work. Both the Act and the rule say that the written signature and date of signing, “along with the date of license expiration, shall be placed adjacent to the seal.” Individual Illinois PE licenses all expire on the same day, November 30 of each odd-numbered year, so that line is identical for every licensee in the state and turns over for everyone at once. A die with the expiration date inside the impression is obsolete every two years.
The durable product carries three lettering elements and nothing else: your name, your license number and the words Licensed Professional Engineer of Illinois. Signature, signing date and expiration date are supplied separately, adjacent to the seal. Legacy devices are protected by statute: any reproducible stamp previously authorized in Illinois, “including those with the words ‘Registered Professional Engineer of Illinois,’” still serves and should not be replaced on that ground alone.
One thing voids the seal outright. “Any document that bears the name of a professional design firm, rather than bearing the name of the individual licensed professional engineer responsible for the document, shall be deemed an invalid seal.” Firm name and design firm registration number belong in the title block, not in the ring. Acorn cuts this seal to 1-5/8 inches. That is our production record rather than an Illinois rule; Section 1380.ILLUSTRATION A is unscaled and labeled a suggested facsimile.
Illinois PE seal requirements at a glance
| Requirement | Illinois rule | Source |
|---|---|---|
| Seal required | Yes | 225 ILCS 325/15(a) and (c) |
| Required elements | Your name; Your license number; The words “Licensed Professional Engineer of Illinois”; Adjacent to the seal: your written signature; Adjacent to the seal: the date of signing; Adjacent to the seal: the date of license expiration | 225 ILCS 325/14 and 325/15(a) |
| Size and shape | Acorn cuts this seal to 1-5/8 inches, and that is a production record rather than a published rule. | Acorn Sales production record, Illinois professional engineer seal |
| Device allowed | The statute requires “a reproducible seal, which may be computer generated”, and the rule adds “a reproducible seal or facsimile”. Reproducible is the operative word: the impression has to survive copying, which rules out a bare embosser as the only device. | 225 ILCS 325/14 |
| Signature and date | Seal, then written signature, then date of signing, then license expiration date, all adjacent to the seal. | 225 ILCS 325/14 and 325/15(a) |
| What must be sealed | Technical submissions, defined by statute as the designs, drawings and specifications that establish the scope of the project and the standard of quality for materials, workmanship, equipment and construction systems, together with the studies, technical reports and calculations prepared in the course of practice. | 225 ILCS 325/15(a) and (d) |
| Electronic seal | Illinois allows a computer generated seal and a computer generated signature and names no technology to produce either. | 225 ILCS 325/14 |
| Renewal and lapse | Every individual professional engineer license expires on November 30 of each odd-numbered year and is renewed for a two-year period. | 68 Ill. Adm. Code 1380.310(a), (c) and (d) |
| Firm number on documents | Firms must register as professional design firms and the registration number has to appear on the work. | 225 ILCS 325/23 |
| Licensing board | The Illinois State Board of Professional Engineers, which advises the Illinois Department of Financial and Professional Regulation | The Professional Engineering Practice Act of 1989, 225 ILCS 325 (§§ 14 seal, 15 technical submissions, 23 design firm registration), |
Rules for other states are on PE stamp requirements by state.
Is a seal required in Illinois?
Illinois requires a seal Illinois puts the duty in the Act and repeats it in the rule. The Act: “All technical submissions prepared by or under the personal supervision of a professional engineer shall bear that professional engineer’s seal, signature, and license expiration date.” The rule: “A professional engineer shall seal all documents prepared by or under the direct supervision and control of the professional engineer.” The Act also closes the loop at the receiving end: no public entity may accept for filing or approval any technical submission requiring an engineer that does not bear the seal and signature of an Illinois licensed professional engineer.
What must appear on the seal
- Your name
- Your license number
- The words “Licensed Professional Engineer of Illinois”
- Adjacent to the seal: your written signature
- Adjacent to the seal: the date of signing
- Adjacent to the seal: the date of license expiration
The signature, the signing date and the license expiration date sit adjacent to the seal, not inside it. Section 1380.ILLUSTRATION A shows the circular impression carrying only the name and number inside the ring and the three lines printed beneath it. That illustration is expressly “a suggested facsimile of the design and lettering of the seal”, so its artwork is guidance while the three lettering elements in 1380.295(a) are mandatory. Legacy devices are protected by statute: any reproducible stamp previously authorized in Illinois, “including those with the words ‘Registered Professional Engineer of Illinois’”, still serves. What is prohibited is a seal bearing the design firm’s name in place of the individual’s: “Any document that bears the name of a professional design firm, rather than bearing the name of the individual licensed professional engineer responsible for the document, shall be deemed an invalid seal.”
Size and shape
Acorn cuts this seal to 1-5/8 inches, and that is a production record rather than a published rule. The state publishes no dimension, so the figure below is what we make and ship for Illinois licensees rather than something you can point a reviewer at. Section 1380.ILLUSTRATION A is an image carrying no dimension and is labeled a suggested facsimile, which leaves the diameter to the supplier. What the state publishes: Neither 225 ILCS 325/14 nor 68 Ill. Adm. Code 1380.295 states a diameter, and Section 1380.ILLUSTRATION A, added effective January 5, 2023, is an image with no dimension and is labeled a suggested facsimile. Checked the Act, Part 1380 in full, and the illustration itself. The same is true of the structural engineer illustration in Part 1480 and the land surveyor illustration in Part 1270.
Embosser, rubber stamp or digital
The statute requires “a reproducible seal, which may be computer generated”, and the rule adds “a reproducible seal or facsimile”. Reproducible is the operative word: the impression has to survive copying, which rules out a bare embosser as the only device. The signature is the licensee’s choice among three forms, “at his or her sole discretion”: an original signature in the licensee’s handwriting, a scanned copy of the document bearing an original signature, or a signature generated by a computer. The safe buy is an inked rubber stamp for the seal itself, paired with a separate line or stamp for the expiration date, since that date changes every two years.
Signing and dating
Seal, then written signature, then date of signing, then license expiration date, all adjacent to the seal. Illinois does not require the signature to cross the seal. Two distinct dates are in play and buyers conflate them: the date of signing is the day the engineer signs, while the date of license expiration is the statewide renewal date printed on the license. Using the seal is itself a representation that the work was prepared by or under the personal supervision of the engineer, or developed with accepted engineering standards, and that it was prepared and administered with reasonable professional skill and diligence.
The license expiration date has to sit next to the seal
Illinois is one of a handful of states that puts an expiring date on the face of sealed work. Both the Act and the rule say the same thing: the licensee’s written signature and date of signing, “along with the date of license expiration, shall be placed adjacent to the seal.” Illustration A shows it as the third printed line under the impression, reading “License Expires: [Date]”.
Individual Illinois PE licenses all expire on the same day, November 30 of each odd-numbered year. That means the expiration line is identical for every licensee in the state and changes for every licensee on the same date. A stamp that includes the expiration date inside the impression is obsolete the moment the cycle turns. The durable product is a seal carrying only the name, the number and the legend, with the signature, signing date and expiration date supplied separately.
The second trap is firm identification. A technical submission issued by a firm must also carry the corporate or assumed business name and the design firm registration number. Buyers frequently ask for the firm name to be lettered into the round seal. Doing that voids the seal outright: a document whose seal bears the firm name rather than the responsible individual’s name is deemed an invalid seal under 1380.295(a). The firm information belongs in the title block, not in the ring.
Which documents must be sealed
Technical submissions, defined by statute as the designs, drawings and specifications that establish the scope of the project and the standard of quality for materials, workmanship, equipment and construction systems, together with the studies, technical reports and calculations prepared in the course of practice. The rule is broader still: “all documents prepared by or under the direct supervision and control of the professional engineer.” There is no preliminary or draft carve-out in the Illinois seal provisions. Section 15(d) makes it unlawful to affix a seal in a way that masks the true identity of the person who exercised direction, control and supervision.
Electronic and digital seals
Illinois allows a computer generated seal and a computer generated signature and names no technology to produce either. The statute says only that when technical submissions are prepared using a computer or other electronic means, “the seal may be generated by the computer”, and that the licensee may supply a handwritten original, a scan of a document bearing an original signature, or a computer generated signature. No PKI requirement, no certificate authority, no tamper-evidence criteria and no named standard appear in the Act or in Part 1380. That is a genuine gap rather than an omission on this page: Illinois has not adopted the four-part electronic signature test that Ohio, Colorado and many other states use.
Renewal, lapse and retirement
Every individual professional engineer license expires on November 30 of each odd-numbered year and is renewed for a two-year period. Practicing or offering to practice on an expired license is unlicensed activity and grounds for discipline. Because the license expiration date must appear adjacent to the seal, the block next to the seal goes stale on a fixed statewide schedule, and a device that bakes the expiration date into the impression has to be replaced every renewal cycle. The license number does not change on renewal, so the seal impression itself remains good. Design firm registrations run on a different clock and expire on April 30 of each odd-numbered year.
Firm registration
Firms must register as professional design firms and the registration number has to appear on the work. Rule 1380.295(b): “All technical submissions issued by a professional engineering firm, corporation, professional limited liability company, limited liability company or partnership are required to bear the corporate or assumed business name and design firm registration number, in addition to the seal requirements.” The firm has no seal of its own, and a seal carrying the firm name instead of the individual’s name is invalid. Registration is filed under Section 23 of the Act and covers corporations, professional service corporations, professional limited liability companies, limited liability partnerships, limited partnerships, partnerships and any sole proprietorship trading under an assumed name.
What to check before you order
The ring reads exactly Licensed Professional Engineer of Illinois, with your name and license number inside and nothing else. Keep your firm name out of the impression and keep the expiration date out of the die. A legacy Registered Professional Engineer of Illinois device stays valid by statute, so there is no reason to replace one on that ground alone. A structural engineer seal is a different device under a different board and a different Act, and its legend reads Licensed Structural Engineer State of Illinois; a land surveyor seal is a third device, and it must also carry the place of business. Illinois imposes no proof-of-licensure requirement before your seal is made.
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Frequently asked questions
Is a PE seal required in Illinois?
Yes, and the receiving end is closed too. The Act provides that “All technical submissions prepared by or under the personal supervision of a professional engineer shall bear that professional engineer’s seal, signature, and license expiration date,” and 68 Ill. Adm. Code 1380.295(a) adds that a professional engineer shall seal all documents prepared by or under the direct supervision and control of the engineer. No public entity may accept for filing or approval a technical submission requiring an engineer that does not bear the seal and signature of an Illinois licensed professional engineer.
What has to appear on an Illinois PE seal?
Your name, your license number and the words Licensed Professional Engineer of Illinois. Those three lettering elements in 1380.295(a) are mandatory. The signature, the signing date and the license expiration date sit adjacent to the seal rather than inside it. Section 1380.ILLUSTRATION A shows the circular impression carrying only the name and number inside the ring with the three lines printed beneath, and it is expressly “a suggested facsimile of the design and lettering of the seal,” so its artwork is guidance while the lettering elements are not.
What size is an Illinois PE seal?
Not addressed. Neither 225 ILCS 325/14 nor 68 Ill. Adm. Code 1380.295 states a diameter, and Section 1380.ILLUSTRATION A, added effective January 5, 2023, is an image with no dimension on it and is labeled a suggested facsimile. The Act, Part 1380 in full and the illustration itself were checked. The same silence runs through the structural engineer illustration in Part 1480 and the land surveyor illustration in Part 1270. Acorn cuts this seal to 1-5/8 inches. That is our production record rather than an Illinois rule; Section 1380.ILLUSTRATION A is unscaled and labeled a suggested facsimile.
Can I use an embosser in Illinois?
Not on its own. The statute requires “a reproducible seal, which may be computer generated,” and the rule speaks of “a reproducible seal or facsimile.” Reproducible is the operative word: the impression has to survive copying, which a bare emboss does not. An inked rubber stamp for the seal itself, with the expiration date supplied separately, is the workable combination.
Is my old Registered Professional Engineer of Illinois seal still good?
Yes, by statute. Any reproducible stamp previously authorized in Illinois, “including those with the words ‘Registered Professional Engineer of Illinois,’” still serves. A licensee holding one of those devices has no obligation to reorder simply because the current wording reads Licensed rather than Registered.
Which date goes next to an Illinois seal?
Both of them, and buyers conflate them. The order is seal, written signature, date of signing, then date of license expiration, all adjacent to the seal. The date of signing is the day the engineer signs. The date of license expiration is the statewide renewal date printed on the license. Illinois does not require the signature to cross the seal. Using the seal is itself a representation that the work was prepared by or under the personal supervision of the engineer, or developed with accepted engineering standards, and that it was prepared and administered with reasonable professional skill and diligence.
Can I put my firm name on my Illinois seal?
No, and doing it voids the seal. Under 1380.295(a) a document bearing the name of a professional design firm rather than the name of the individual licensed professional engineer responsible for it is deemed to bear an invalid seal. Firm identification is still required, but as separate text: rule 1380.295(b) provides that technical submissions issued by a firm, corporation, professional limited liability company, limited liability company or partnership “are required to bear the corporate or assumed business name and design firm registration number, in addition to the seal requirements.” That belongs in the title block.
Can I sign and seal electronically in Illinois?
Yes, and the state names no technology for either. The statute says that when technical submissions are prepared using a computer or other electronic means “the seal may be generated by the computer,” and the licensee may supply, “at his or her sole discretion,” an original signature in handwriting, a scanned copy of a document bearing an original signature, or a signature generated by a computer. No public key infrastructure requirement, no certificate authority, no tamper-evidence criteria and no named standard appear in the Act or in Part 1380. Illinois has not adopted the four-part electronic signature test that Ohio, Colorado and many other states use.
Which Illinois documents have to be sealed?
Technical submissions, defined by statute as the designs, drawings and specifications that establish the scope of the project and the standard of quality for materials, workmanship, equipment and construction systems, together with the studies, technical reports and calculations prepared in the course of practice. The rule reaches further, to “all documents prepared by or under the direct supervision and control of the professional engineer.” There is no preliminary or draft carve-out in the Illinois seal provisions. Section 15(d) makes it unlawful to affix a seal in a way that masks the true identity of the person who exercised direction, control and supervision.
Do I need a new Illinois seal when I renew?
Only if the expiration date was built into the impression. Individual licenses expire November 30 of each odd-numbered year and renew for a two-year period, and practicing on an expired license is unlicensed activity and grounds for discipline. The license number does not change on renewal, so a seal carrying only the name, number and legend stays good indefinitely. Note that design firm registrations run on a different clock and expire April 30 of each odd-numbered year.
Is a structural engineer seal the same product in Illinois?
No. Structural engineers are licensed under a different Act and a different Part, and the legend reads Licensed Structural Engineer State of Illinois. Land surveyors are a third product under 225 ILCS 330/15 and 68 Ill. Adm. Code 1270.58, with the legend Professional Land Surveyor, State of Illinois, and uniquely the surveyor seal must also contain the surveyor’s place of business. The three sets of seal rules are not interchangeable.
