A Wisconsin sole proprietorship can't be "converted" because it was never an entity. You form a new LLC (Articles of Organization, Form 502, $130 online), then move the business into it. A single-member LLC can usually keep your existing EIN and your DOR tax account; you need a new EIN only if you'll have employees, add an owner, or elect corporate taxation. Employers tell DWD within 30 days. Then: new bank account, assigned contracts, updated insurance and licenses.
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Most people who search "convert sole proprietorship to LLC" have been running a real business for a while. There is revenue, a client list, a bank account with the business name on it, a seller's permit, maybe an employee. The question isn't whether to form an LLC (our LLC vs. sole proprietorship guide covers that); it's how to move everything that already exists into one without breaking a contract, a tax account, or payroll.
This guide is the order of operations for Wisconsin specifically: the DFI filing, the IRS rules on whether your EIN survives, what the Department of Revenue and DWD each expect, and the checklist for moving the rest of the business over.
What "converting" actually means
Wisconsin has a statutory conversion process (Wis. Stat. § 183.1041), but it is for entities: a corporation becoming an LLC, an out-of-state LLC becoming a Wisconsin one. A sole proprietorship isn't an entity. It is you, doing business, possibly under a registered trade name. There is nothing on file with the Department of Financial Institutions to convert.
So the legal mechanics are three separate things:
- Form the LLC. A brand-new entity, with its own name on the DFI's records and its own effective date.
- Contribute the business to it. Equipment, inventory, the client list, the domain, the trade name. For a single-member LLC this is a non-event for income tax; the IRS disregards the LLC and nothing changes on your return.
- Retire the proprietorship's accounts or re-point them at the LLC: the bank account, DOR registration, DWD account, insurance, licenses, contracts.
What changes: the business becomes a separate legal person. Contracts, debts, and lawsuits land on the LLC, not on you, as long as you keep it separate (more on that below). What doesn't change by default: taxes. A single-member LLC is disregarded for federal income tax and Wisconsin follows; you keep filing Schedule C and paying self-employment tax. If you want the tax picture to change too, that is a separate, later decision (the S-corp election).
Step 1: Pick the switch date
The cleanest conversions happen on the first day of a month, quarter, or year, so that one set of books ends and the next begins without a split period. Wisconsin makes this easy: Articles of Organization can carry a delayed effective date up to 90 days after filing (Wis. Stat. § 183.0207(3)). File in October, November, or December with a January 1 effective date and the old year stays entirely on the proprietorship.
Two things key off that effective date. Your annual report ($25) is due each year by the end of the calendar quarter in which the Articles became effective (§ 183.0212(3)(a)). And every account you re-title (DOR, DWD, bank, insurance) should use the same date, so there is one clear line between "me" and "the LLC."
Step 2: Clear the name
The LLC's name must contain "LLC," "L.L.C.," "Limited Liability Company," or a permitted variant (§ 183.0112(1)), and it must be distinguishable on the DFI's records from every existing entity, reserved name, and registered name (§ 183.0112(2)). Run it through the free entity search before you do anything else.
The trap for existing businesses: a trade name registered under ch. 132 is a different system from entity names. Registering "Lakeside Woodworks" as a trade name years ago did not reserve "Lakeside Woodworks LLC." If someone formed an LLC under that name since, the DFI will reject yours, and the fact that you used the name first is a trademark question, not a filing question. Our naming guide walks through the full search.
If the name is clear and you are timing a delayed filing, a name reservation holds it for 120 days for $15 (§ 183.0113). If the LLC ends up with a different legal name than the one customers know, you can assign your registered trade name to the LLC; the DFI records the assignment for $15 (§ 132.01(3)), and the LLC keeps trading under it.
Step 3: File the Articles of Organization
This is the same filing as any new Wisconsin LLC: Form 502, $130 online ($170 by paper), typically processed within a business day when filed online. You will need:
- The LLC name from Step 2
- A registered agent with a Wisconsin street address and an email (§ 183.0115). You can be your own agent if you have a Wisconsin street address you're willing to publish and staff during business hours; many owners use a registered agent service ($59/year) instead.
- The organizer's name and address (you)
- Optionally, a statement that the LLC is manager-managed (the default is member-managed) and the delayed effective date from Step 1
Our full formation guide covers each field. Nothing on the form asks about the existing sole proprietorship; as far as the DFI is concerned, this is a new company.
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Step 4: Sort out the EIN (the rule most guides get wrong)
The IRS publishes exactly when a new EIN is required, and the answer for a sole proprietor forming an LLC is "it depends on employees and owners," not "always." From the IRS's own list:
| Your situation after forming the LLC | New EIN? | Why |
|---|---|---|
| Single owner, no employees, no excise tax, default (disregarded) taxation | No | The IRS lets you "use your sole proprietor EIN for your single-member LLC." If you never had an EIN and used your SSN, you still don't strictly need one, but banks and payment processors will want one in the LLC's name. |
| You have, or will hire, employees | Yes | For wages paid after January 1, 2009, a single-member LLC must report and pay employment taxes under its own name and EIN. Get it before the first payroll run under the LLC. |
| You are adding a co-owner | Yes | A multi-member LLC is a partnership for tax purposes. Sole proprietors who "form a partnership" need a new EIN, and the LLC files Form 1065 going forward. |
| You elect S-corp or C-corp taxation | Usually yes | The IRS does not require a new EIN merely to change an existing LLC's tax election, but an LLC that elects corporate taxation at formation has to get its own EIN; the sole-proprietor number does not carry into a corporation. |
Applying is free and takes minutes on the IRS site. One practical note for the "no new EIN" case: a disregarded LLC's Form W-9 still shows your name on line 1 and the LLC's name on line 2, with your SSN or sole-proprietor EIN, not an EIN issued to the LLC. Clients who 1099 you will ask for a new W-9 either way; this is what it should say.
Step 5: Update the Wisconsin Department of Revenue
Your seller's permit, use tax certificate, and withholding account all live under a Business Tax Registration (BTR): $20 for the first two years, $10 per renewal after that. What happens to it depends on the same EIN question:
- Single-member LLC, disregarded for income tax: the DOR keeps your existing tax account number and adds the LLC to it. You don't file a new registration; you report the new business name through My Tax Account. Your seller's permit continues under the LLC.
- Anything that produces a new federal EIN (a multi-member LLC, corporate taxation): the DOR treats it as a new taxpayer. File a new Business Tax Registration, pay the $20, and close the proprietorship's accounts as of the switch date. A seller's permit is not transferable; the LLC needs its own.
Either way, file the proprietorship's final sales and withholding returns through the switch date, and start the LLC's on the day after. Overlapping periods are where penalties come from.
Step 6: If you have employees, tell DWD and your insurer
Unemployment insurance. DWD treats a transfer between businesses owned by the same people, which is exactly what a sole proprietor forming an LLC is, as a mandatory successorship: the LLC takes over your UI account and its experience rating rather than starting fresh. You have 30 days from the transfer to file a Report of Business Transfer (UCT-115); the rules are in Part 6 of the UI Employer Handbook. DWD classifies a single-member LLC as a sole proprietorship and a multi-member LLC as a partnership unless the LLC has elected corporate taxation.
Worker's compensation. Ask your carrier to reissue the policy with the LLC as the named insured, effective on the switch date. As an LLC member you are not automatically covered as an employee; decide whether you want to elect coverage for yourself when the policy is rewritten.
Step 7: Move everything else over
Work down this list in the week around the effective date. Nothing on it is hard; the damage comes from the items people skip.
- Bank account. Open a new account in the LLC's name. Banks typically ask for the filed Articles, the EIN confirmation letter, and an operating agreement; some also want a Certificate of Status ($10). Move recurring deposits and autopays, let outstanding checks clear, then close the old account. Do not keep running the business out of the proprietorship's account "for now."
- Contracts and leases. Each one is between the other party and you. Either sign a short assignment to the LLC (check for anti-assignment or landlord-consent clauses first) or, for anything renewing soon, just sign the renewal in the LLC's name. Going forward, sign as "Lakeside Woodworks LLC, by Jane Smith, Member," never as yourself.
- Insurance. General liability, professional liability, auto, and property policies need the LLC as the named insured. A policy still in your personal name may not respond to a claim against the LLC.
- Licenses and permits. Professional licenses stay with you personally. Local business licenses, health permits, and state registrations issued to a business often have to be reissued in the entity's name; ask each issuer rather than assume.
- Payment processors and marketplaces. Stripe, Square, Shopify, Etsy, and the rest all key payouts to a legal entity, a tax ID, and a bank account. Update all three together, or deposits stop.
- Customers and vendors. New W-9 to anyone who 1099s you (see Step 4), new remit-to details on invoices, and the LLC's name in your terms, privacy policy, and email signature.
- Trade name and brand. Assign the ch. 132 registration to the LLC ($15) if you're keeping it, and update the Google Business Profile, domain registrant, and social accounts to the entity.
Step 8: Keep the shield you just built
The liability protection only works if the LLC is actually separate from you. That means an operating agreement (even with one member; without one, ch. 183's defaults govern and banks will ask anyway), separate accounts with no personal spending, contracts signed in your capacity as member, the annual report filed each year, and a registered agent who is actually reachable. Miss the report for a year and the DFI can administratively dissolve the LLC, which puts you right back where you started.
Assuming a DBA filing "converted" the business (it didn't; a trade name is not an entity). Running payroll under the old sole-proprietor EIN after the LLC has employees. Leaving the bank account and insurance in your own name. And signing the first big contract after the switch as yourself, which makes you personally liable on it no matter what the DFI's records say.
What it costs
| Item | Cost | Notes |
|---|---|---|
| Articles of Organization (Form 502) | $130 online / $170 paper | The only mandatory fee |
| Expedited processing | +$100 | Optional; next business day. Counter tiers in our expedite guide |
| Name reservation | $15 | Optional; 120 days |
| Trade name assignment to the LLC | $15 | Optional; only if you keep a ch. 132 registration |
| EIN | $0 | Free from the IRS, if you need a new one |
| DOR Business Tax Registration | $0 or $20 | $0 for a disregarded single-member LLC (same account); $20 if a new registration is required |
| DWD Report of Business Transfer | $0 | Employers only; within 30 days |
| Annual report | $25/year | Due by the end of your formation quarter each year |
| Registered agent service | $59/year | Optional; you can serve as your own agent |
| Anchor Filings LLC formation | $159 | Includes the $130 state fee, Articles, operating agreement, and portal |
Sources & Statutory References
- Wis. Stat. § 183.0112: permitted LLC names; distinguishable-name requirement; consent-based exceptions
- Wis. Stat. § 183.0113: name reservation (120 days)
- Wis. Stat. § 183.0115: registered agent and registered office
- Wis. Stat. § 183.0207: effective date of filed records; delayed effective date up to 90 days
- Wis. Stat. § 183.0212: annual report due date keyed to the formation quarter
- Wis. Stat. § 183.1041: statutory conversion (entities only)
- Wis. Stat. § 132.01: registration and assignment of marks and trade names; $15 recording fee
- IRS, When to get a new EIN: rules for sole proprietors and single-member LLCs
- IRS, Single member limited liability companies: disregarded-entity reporting, employment-tax EIN rule, Form W-9 instructions
- Wisconsin DOR, Making Changes to My Account: entity-type changes, the single-member LLC exception, new-FEIN rule
- Wisconsin DOR, Sales and Use Tax Permits: seller's permits are not transferable
- Wisconsin DOR, Business Tax Registration: $20 initial fee, $10 biennial renewal
- Wisconsin DWD, UI Employer Handbook, Part 6: Business Transfers: mandatory successorship for commonly owned businesses; 30-day reporting; Form UCT-115
Statutes, fees, and procedures cited here are current as of October 2026 and subject to amendment. Verify operative text on the Wisconsin Legislature's site and the agency pages linked above before filing. This guide is general information, not legal or tax advice.
Frequently Asked Questions
Not always. The IRS lets a single-member LLC keep using the owner's sole-proprietor EIN if it stays taxed as a disregarded entity and has no employees and no excise tax. You must get a new EIN if the LLC will have employees (it has to report payroll under its own name and EIN), if you add a co-owner (the LLC becomes a partnership), or if you elect corporate taxation. Getting one is free at irs.gov and takes a few minutes.
Usually, with "LLC" added. The LLC's name has to be distinguishable on the DFI's records from existing entities, reserved names, and registered names (Wis. Stat. § 183.0112(2)). A trade-name registration under ch. 132 is a separate system and does not reserve an entity name, so run the entity search before you file. If the LLC name differs from the name customers know, you can assign your registered trade name to the LLC for a $15 recording fee.
Not with the DFI. A sole proprietorship was never registered there, so there is nothing to dissolve. The closing work is with the Wisconsin Department of Revenue (update or re-register your business tax accounts), DWD if you have employees, your bank, and your insurer. For a disregarded single-member LLC, your federal return does not change either: you keep filing Schedule C.
By default, no. A single-member LLC is disregarded for federal and Wisconsin income tax, so the business still goes on Schedule C and you still pay self-employment tax. What changes is the liability shield, not the tax bill. If you want the tax bill to change, that is a separate decision (an S-corp election) covered in our LLC vs. S-Corp guide.
If you are a sole proprietor becoming a single-member LLC that is disregarded for Wisconsin income tax, the DOR keeps your tax account number and adds the LLC to it; you only have to report the new name. If the change produces a new federal EIN (a multi-member LLC or an S-corp election), you file a new Business Tax Registration; the old permit is not transferable.
Yes. Wisconsin lets you file Articles of Organization now with a delayed effective date up to 90 days out (Wis. Stat. § 183.0207(3)). Filing in Q4 for a January 1 start keeps the old year on the proprietorship's books and the new year on the LLC's.
Almost always. Banks open LLC accounts in the entity's name against the filed Articles, the EIN letter, and usually an operating agreement; most will not retitle a personal or sole-proprietor account. Keeping LLC money in the old account is also the fastest way to lose the liability shield you just paid for.
