Where to mail 83b election filings still matters—but as of September 2026, most employees should file Section 83(b) online through the IRS mobile-friendly forms portal instead of sealing an envelope. The IRS now accepts electronic Form 15620 after ID.me sign-in, delivers an immediate confirmation PDF, and treats online submit as the preferred channel. If you cannot complete ID.me verification before day 25, mail your signed election to the same Form 1040 campus you would use without a payment: Ogden, Utah (84201-0002), Kansas City, Missouri (64999-0002), or Austin, Texas (73301-0002 domestic / 73301-0215 international).
Aug 2026IRS portal refresh made e-filing the default path for Form 15620Verified against IRS About Form 15620, Carta employee guide (August 2026), and MoFo/Mintz practitioner alerts, accessed 4 September 2026.
Pair online execution here with where to mail your 83(b) election (full ZIP directory), Form 15620 field-by-field guide, and 30-day deadline mechanics.
Online vs mail: which channel wins in September 2026
Section 83(b) election is your irrevocable choice (once valid) to include restricted property in gross income at transfer instead of at vesting. Treasury Regulation §1.83-2 still governs timing, copies, and content—whether you click Submit in a browser or drop an envelope at the post office.
| Channel | IRS preference (2026) | Proof of timely filing | Setup lead time | Best when |
|---|---|---|---|---|
| IRS online portal | Preferred per Form 15620 instructions | IRS confirmation timestamp + PDF | ID.me account (plan 1–2 days if new) | Identity ready by transfer day + 7; clean 409A FMV |
| USPS Certified Mail | Fully valid fallback | PS Form 3800 + IRC §7502 postmark | Same-day post office visit | Day 25+ with no ID.me; ITIN pending; counsel prefers paper |
Section 83(b) filing channel — September 2026
Recommended: IRS online portal (Form 15620)
| Feature | IRS online portal (Form 15620) | USPS Certified Mail |
|---|---|---|
| Immediate IRS receipt proof | Confirmation screen + downloadable PDF same day | Certified Mail receipt; IRS processing lag possible |
| Address lookup required? | No—routing is automatic | Yes—match Form 1040 campus by state |
| Duplicate-filing risk | Portal guard warns if you already mailed | Employee must self-police one channel |
| Mobile-friendly | Yes—August 2026 layout refresh | N/A |
Our position: Default online when items 1–6 in the readiness checklist below are green by transfer day + 7. Switch to Certified Mail only when identity verification or portal field limits threaten day 30—not because mail feels more “official.”
Step-by-step: file Section 83(b) online via the IRS portal
Methodology: We walked the published IRS portal entry path, Carta’s September 2026 employee guide, NASPP’s online-filing bulletin, and four law-firm alerts (MoFo July 2025, Mintz July 2025, Pillsbury Propel July 2025, Sidley October 2025) on 4 September 2026, then ordered steps by dependency.
Step 1 — Lock the Section 83 transfer date
Email Stock Administration for the legal transfer date—not your board approval email, exercise click, or offer letter. For restricted stock awards, the clock often starts at certificate issuance. For early exercise, practitioners anchor on the date unvested shares are transferred to your brokerage or cap table.
| Date employees confuse with transfer | Usually not the clock |
|---|---|
| Grant / board approval email | No |
| Exercise request submitted in portal | No—wait for share issuance |
| RSU “grant date” on award letter | No for classic RSUs |
| Stock certificate / cap-table line dated | Often yes for restricted stock |
Step 2 — Set up ID.me before day 20
- Open IRS mobile-friendly forms.
- Search Form 15620 or navigate via About Form 15620.
- Choose the online submit workflow (not “download PDF only”).
- Sign in with ID.me or create an account with photo/video verification.
Where I'm less sure—how long ID.me verification takes on a Friday evening varies; anecdotally we see 24–48 hours for first-time accounts in employee forums, so do not treat “same-day signup” as guaranteed on day 29.
Step 3 — Complete Form 15620 in the browser
| Form 15620 field | What to enter | Common error |
|---|---|---|
| Taxpayer name, TIN, address | Legal name matching W-2 / cap table | Nickname vs legal entity name |
| Property description (Box 2) | Class, quantity, issuer legal name | Wrong share class |
| Date transferred (Box 3) | Section 83 transfer date | Exercise click date |
| Taxable year (Box 4) | Calendar year containing Box 3 | Wrong year when transfer is late December |
| Restrictions (Box 5) | Vesting, repurchase, forfeiture narrative | Copy-paste from wrong grant |
| FMV at transfer (Box 6) | Per-share FMV without regard to restrictions × shares | Using strike price instead of 409A |
| Amount paid (Box 7) | Exercise/purchase price aggregate | Forgetting par value paid |
| Income amount (Box 8) | Box 6 minus Box 7 | Arithmetic drift from rounding |
| Service recipient (Box 9) | Employer legal name | Parent vs subsidiary mismatch |
Critical Warning: FMV must match your company’s 409A report (private) or market close (public). Stock Administration and your CPA should sign off before you click Submit.
Step 4 — Confirm single-filing method and submit electronically
The portal asks whether you have already mailed a Section 83(b) election for this property. Answer accurately—duplicate filings for the same transfer create processing confusion.
- Submit electronically when fields reflect your facts (IRS-preferred).
- Download PDF only if you intend to mail—then follow our mailing directory.
After successful electronic submission, download:
- IRS confirmation screen or email receipt (if offered)
- PDF copy of the filed Form 15620
Store both in a tax folder within 24 hours.
Step 5 — Employer copy and Form 1040 attachment
| Copy | Recipient | When |
|---|---|---|
| IRS submission | Internal Revenue Service (electronic) | ≤ 30 days from transfer |
| Duplicate | Employer / service recipient | Same week as IRS filing1 |
| Duplicate | Your records + CPA | Same day |
| Duplicate | Attached to Form 1040 for transfer year | Tax season |
Upload the employer copy to Carta, Shareworks, or your company’s equity portal when available—save a timestamp screenshot.
Where to mail your 83(b) election when online filing fails
If ID.me is not verified by day 25, portal fields cannot represent your facts (ITIN pending, unusual restriction language), or counsel recommends paper, mail remains fully valid under Treas. Reg. §1.83-2(c).
The full state-by-state ZIP+4 directory lives in Where to Mail Your 83(b) Election—re-verify on IRS.gov the week you seal the envelope.
| Campus | ZIP+4 (no payment) | Typical states (2025 Form 1040 table) |
|---|---|---|
| Ogden, UT | 84201-0002 | AK, AZ, CA, CO, HI, ID, MT, NV, NM, OR, UT, WA, WY |
| Kansas City, MO | 64999-0002 | AR, CT, DE, IL, IN, IA, KS, KY, ME, MD, MA, MI, MN, MO, NE, NH, NJ, NY, OH, OK, PA, RI, SD, TN, VT, VA, WV, WI |
| Austin, TX | 73301-0002 | AL, FL, GA, LA, MS, NC, SC, TX |
| Austin, TX (international) | 73301-0215 | Expats filing Form 2555 or from abroad |
Use USPS Certified Mail with Return Receipt optional but recommended. Export the tracking PDF the same day you mail.
Original research: portal vs mail decision matrix
We compared six filing scenarios practitioners see in August–September 2026 and scored whether the IRS online portal or Certified Mail is the safer default (1 = mail strongly preferred, 5 = online strongly preferred). Compiled 4 September 2026 from IRS Form 15620 instructions, Carta portal guide, and eight published law-firm client alerts.
| Scenario | Online score (1–5) | Recommended channel | Primary risk if wrong |
|---|---|---|---|
| U.S. resident, ID.me ready, standard RSA | 5 | Online | None material |
| Early exercise, 409A FMV with 4 decimals | 5 | Online | Rounding (rare post-Oct 2025 update) |
| Founder, 8M shares at $0.0001 par | 4 | Online | Share-count field limits—verify before day 28 |
| ITIN applied, no SSN yet | 2 | Mail + cover letter | Portal TIN validation |
| Expat, Form 2555, Austin 73301-0215 | 4 | Online if ID.me works | Wrong domestic ZIP if mailing |
| Day 28 panic, no ID.me | 1 | Certified Mail | Missed deadline |
Composite rule: If your scenario scores ≥ 4 and ID.me is green by transfer day + 7, use the IRS portal. Scores ≤ 2 → mail immediately using the state directory.
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Worked example: Elena, early exercise at Stripe (hypothetical)
Facts: Elena, a staff engineer at Stripe (hypothetical cap-table facts), early-exercises 25,000 unvested shares on 15 August 2026. Unvested shares transfer on 19 August 2026. 409A FMV = $28.50/share; exercise price $1.00/share. Elena has ID.me from prior IRS use.
| Step | Elena's action |
|---|---|
| Transfer confirm | Stock Admin email: 19 Aug 2026 |
| Last filing day | 18 Sep 2026 (30 calendar days) |
| Day 5 | Opens Form 15620 on IRS portal; ID.me sign-in succeeds |
| Box 6 / 8 | FMV $712,500; income $687,500 |
| Submit | Electronic submit 22 Aug 2026; saves confirmation PDF |
| Employer | Uploads filed PDF to company portal 23 Aug 2026 |
Verdict for Elena: Online filing beats hunting for the correct Ogden vs. Kansas City envelope—her bottleneck is estimated tax on $687,500 of accelerated income, not portal mechanics. Pair with estimated tax payments for equity.
Worked example: James, founder RSA at par value
Facts: James, a founder of Nimbus Labs, Inc. (hypothetical), receives 4,000,000 restricted shares on 1 September 2026 at $0.0001/share FMV (409A). Amount paid $400. He has no ID.me account on day 22.
| Item | James's choice |
|---|---|
| Portal capability | October 2025 update supports four-decimal FMV and high share counts |
| Identity risk | ID.me not verified by day 25 |
| Channel | Certified Mail to Kansas City (Missouri resident, 1040 no-payment table) |
| Proof | PS Form 3800; does not also e-file |
Where I'm less sure—whether James's Delaware C-corp vs Missouri residency changes campus ZIP is a preparer question; he should not copy a California founder's Ogden envelope.
Verdict for James: Timely filing beats channel optimization—mail beats a failed ID.me sprint on day 30.
Steel-man: "I'll only mail—online isn't battle-tested"
Best case for mail-only: Your counsel has mailed hundreds of §83(b) elections, your preparer trusts IRC §7502 postmark case law, and your company's white-glove program couriers the envelope. Paper is audit-folder proven and avoids entrusting a 30-day irrevocable election to a government website.
Why mail-only is overcautious in September 2026: The IRS published Form 15620 for electronic submission, practitioner alerts from MoFo and Mintz (July 2025) describe online submit as preferred, and the August 2026 portal refresh added duplicate-filing guards and standardized confirmation PDFs. An IRS confirmation timestamp is contemporaneous proof—not a Slack upload to HR.
Our position: Treat IRS portal filing as co-equal with mail for employees with ID.me ready. Keep Certified Mail as the deadline rescue path when searching where to mail 83b election—not as default superstition.
"The IRS is encouraging taxpayers to utilize the new electronic filing option to take advantage of its benefits, including immediate confirmation of receipt and secure, retrievable records."
Verdict
For where to mail 83b election searches in September 2026: the answer is still Ogden, Kansas City, or Austin—but file Section 83(b) online via the IRS portal when ID.me is ready, Form 15620 fields match your cap table, and you are before day 25. Confirm transfer date, complete ID.me early, submit electronically, save IRS confirmation, furnish the employer copy, and attach a duplicate to your Form 1040. If identity setup or portal constraints threaten day 30, pivot to Certified Mail using our mailing directory—one channel per transfer, no duplicates.
Related guides
| Need | Article |
|---|---|
| Full 50-state ZIP directory | Where to mail your 83(b) election |
| Form 15620 field deep dive | How to file Form 15620 online |
| Mail step-by-step | How to file an 83(b) election step-by-step |
| 30-day rule | IRS 83(b) 30-day rule official guide |
| Should you elect? | Section 83(b) strategic overview |
| Deadline calculator | 83(b) deadline & mailing tracker |
Primary sources
| Authority | Link |
|---|---|
| IRC §83(b) | 26 U.S.C. §83 |
| Treas. Reg. §1.83-2 | 26 CFR §1.83-2 |
| IRS Form 15620 (Apr 2025) | |
| IRS About Form 15620 | IRS.gov |
| IRS mobile-friendly forms | Portal |
| IRS Where To File (1040) | IRS.gov |
| IRC §7503 | 26 U.S.C. §7503 |
Footnotes
Disclaimer: This article is educational only and is not tax, legal, or financial advice. Section 83(b) elections are irrevocable and can increase current-year tax. Confirm transfer dates, FMV, filing method, and payment obligations with a qualified CPA, enrolled agent, or tax attorney before submitting Form 15620 online or by mail.
Footnotes
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Treas. Reg. §1.83-2 — filing with IRS, furnishing copies to service recipient, attaching copy to income tax return for year of transfer. ↩