Key Takeaways
- EIN = business "SSN" (9-digit federal tax ID).
- Required if: employees, corporation, partnership, retirement plan.
- Sole prop: SSN sufficient unless employees or retirement plan.
- New EIN required: incorporation, death of sole prop, new partnership.
- NOT required: name change, S-election, check-the-box.
- Responsible Party change: report within 60 days (Form 8822-B).
Last updated: January 2026
Employer Identification Number (EIN)
Why This Matters for the Exam
EIN requirements are frequently tested. Know when a new EIN is required vs. when the old one continues.
Expect at least 2-3 questions on EIN.
When EIN Is Required
| Trigger | EIN Required |
|---|---|
| Have employees | Yes |
| Corporation or Partnership | Yes |
| Trust or Estate (Form 1041) | Yes |
| Retirement plan (Keogh, 401k) | Yes |
| Excise tax returns | Yes |
| Sole prop (no employees) | SSN sufficient |
When NEW EIN Is Required
| Change | New EIN? |
|---|---|
| Sole prop incorporates | YES |
| Death of sole proprietor | YES (for estate) |
| Partnership terminates, new forms | YES |
| Corporation receives new charter | YES |
When NEW EIN Is NOT Required
| Change | New EIN? |
|---|---|
| Name change | NO |
| Address change | NO |
| C-Corp elects S-status | NO |
| LLC check-the-box election | NO |
| Partnership adds partner | NO (usually) |
Form SS-4
| Method | Details |
|---|---|
| Online | Fastest (Mon-Fri 7am-10pm EST) |
| Fax/Mail | Required if no US SSN/ITIN |
| Third-party designee | EA/CPA can apply on behalf |
Responsible Party Rule
| Element | Requirement |
|---|---|
| Definition | Individual with control over funds/assets |
| Change reporting | 60 days (Form 8822-B) |
| Risk | Outdated info = notices to wrong person |
Real-World Scenario
Scenario: Sole proprietor incorporates and receives new state charter.
- Old EIN: Cannot continue (different legal entity).
- Action: Apply for new EIN using Form SS-4.
- Timeline: Immediate upon incorporation.
On the Exam
Expect 2-3 questions on EIN, typically:
- New EIN Questions: "Sole prop incorporates—new EIN?"
- Responsible Party Questions: "How many days to report change?"
- S-Election Questions: "Does S-election require new EIN?"
The key is to remember: New EIN if structure changes (incorporation, death). Same EIN if name/address/S-election. Responsible Party = 60 days.
Test Your Knowledge
Sole proprietor incorporates with new state charter. New EIN required?
A
B
C
D
Test Your Knowledge
Deceased sole proprietor business continues 6 months. EIN requirement?
A
B
C
D
Test Your Knowledge
Responsible Party changes. Report within how many days?
A
B
C
D