Wisconsin Withholding Tax Registration: Form BTR-101 and WT-4 Setup

To register for Wisconsin withholding tax, file Form BTR-101 with the Wisconsin Department of Revenue before you issue your first paycheck, pay the $20 registration fee, and wait for the department to assign you an account number and filing frequency. You can submit the application online through the My Tax Account portal at tap.revenue.wi.gov or mail a paper form to Madison. Online filers usually get an account number by email within one to two business days; paper filers should plan on several weeks.

Do You Actually Need to Register

Wisconsin’s withholding obligation has two parts, and both have to be true before you need an account. First, you must pay wages to at least one Wisconsin resident (no matter where they do the work) or to a nonresident who performs services inside Wisconsin. Second, your business must have a Wisconsin connection: organized under Wisconsin law, licensed to do business here, or otherwise conducting business in the state.¹

If both are true, state law requires you to deduct and withhold income tax from every wage payment using the department’s published tables or an approved alternative method.² There is no minimum payroll or employee count that lets you skip registration. One qualifying employee is enough.

A company based entirely outside Wisconsin, with no employees working in the state, has no registration duty, even if it sometimes sells products to Wisconsin customers.

What to Gather Before You File

Form BTR-101 is the single application for all Wisconsin business tax registrations. For a withholding-only setup, you work through Part C (general business information) and Part G (withholding details), and leave the rest alone.³

Pull these together before you start:

Your Federal Employer Identification Number (FEIN). You cannot complete the withholding section without it, so get it from the IRS first if you don’t already have one.
Your legal business name and entity type (LLC, S-corporation, sole proprietorship, and so on), exactly as they appear on your organizing documents.
Your six-digit NAICS code. If you don’t know it, look it up on the Census Bureau’s NAICS site.
Social Security numbers for every owner, officer, member, or partner you’ll list in Part H.
The date you expect to begin paying wages subject to Wisconsin withholding. This sets your initial reporting period.
Your physical business address and a separate mailing address if correspondence should go somewhere else.

The $20 fee is not a one-time charge. It covers a two-year period, and a $10 renewal is due every two years after that.⁴ Put the renewal date on your calendar when you register; letting it lapse creates problems that are easier to avoid than to fix.

Filing Online or by Mail

The faster route is online. Go to tap.revenue.wi.gov, work through the registration prompts, pay the $20 fee electronically, and keep the confirmation page. Most online registrants get an email with their new account number within one to two business days, and the paper permit follows by mail within seven to ten business days.⁵

If you’d rather file on paper, print Form BTR-101 from the Department of Revenue site, fill it out in black ink, and mail it with a $20 check to:

Wisconsin Department of Revenue
PO Box 8902
Madison, WI 53708-8902³

Paper applications take several weeks to process, so file well before your first payroll run.

Before You Run Your First Payroll

Having the account open is not quite enough. Two more things need to happen before paychecks go out.

Collect a Form WT-4 From Every Employee

Wisconsin uses its own withholding certificate, Form WT-4, which is separate from the federal W-4. Every new hire has to give you one, and the figures on it determine how much Wisconsin tax you withhold from each check.⁶ If an employee fails to turn one in, you must withhold without allowing any exemptions, which usually means a larger deduction than the employee expects.

Report the Hire to the State Directory

Every new or rehired employee must be reported to the Wisconsin State Directory of New Hires within 20 days of the hire date. The 20-day clock also starts over for an employee returning after an unpaid gap of more than 60 days. This is a separate obligation administered by the Department of Workforce Development, not the Department of Revenue, so completing your BTR-101 does not satisfy it. The easiest way to report is online at wi-newhire.com; you can also mail or fax the employee’s completed WT-4 or federal W-4 (as long as it shows date of birth and date of hire) to PO Box 14431, Madison, WI 53708.⁷

What You’ll Owe After You Register

Once your account is active, the department assigns a filing frequency based on the withholding amounts you estimated on the application. The frequency can be adjusted later as your actual payroll grows or shrinks, and the department will tell you in writing if it changes, usually effective at the start of the next calendar year.⁸

The statutory tiers work like this:⁹

Quarterly is the default. Deposit reports and payments are due by the last day of the month after each quarter closes: April 30, July 31, October 31, and January 31.
Monthly kicks in when your quarterly withholding exceeds $300 and the department notifies you in writing. Each month’s report and payment are due by the last day of the following month.
Semi-monthly applies when your quarterly withholding exceeds $5,000. Tax withheld from the 1st through the 15th is due by the last day of that month; tax withheld from the 16th through the end of the month is due by the 15th of the following month.⁸

The Annual Reconciliation: Form WT-7

No matter which deposit schedule you’re on, every employer with an active Wisconsin withholding account files Form WT-7, the annual reconciliation, by January 31 for the prior calendar year. The WT-7 totals the wages paid and the Wisconsin tax withheld, and you file your W-2s with it.¹⁰

Form WT-7 must be filed electronically unless the department approves a hardship waiver on Form EFT-102. If you have 10 or more wage statements, electronic W-2 filing is also mandatory.¹¹ You can file through My Tax Account, third-party payroll software, or the department’s TeleFile phone system. If you close the business mid-year, the WT-7 is due within 30 days of shutting down, not the following January.¹⁰

What Happens If You Get It Wrong

Wisconsin’s penalties compound quickly, and some reach you personally.

A late deposit report draws a 5% penalty on the unpaid amount for the first month, plus 5% for each additional month or partial month, up to 25%.¹²
Incomplete reports or a failure to deposit carry a 25% penalty on the amount not properly reported, withheld, or deposited, unless you show good cause rather than neglect.¹²
Intentional failure to withhold triggers a 100% penalty on the unpaid tax, plus accrued interest and other penalties. The statute places personal liability on officers, members, and responsible employees, and that liability survives dissolution of the business.¹²
Delinquent amounts accrue interest at 1.5% per month, or 18% annualized, from the deposit due date until paid. The department has discretion to reduce the rate to 12% per year where it finds that result fair and equitable.

Construction employers face an additional exposure: a $25,000 fine per violation for willfully misclassifying employees as independent contractors to dodge withholding.⁹

The personal liability piece catches people off guard. If you’re a corporate officer, an LLC member, or anyone with a duty to see that the taxes get deposited, the department can pursue you individually for the full amount. The business entity does not shield you from this one.

1
Wisconsin State Legislature. General Withholding Tax Questions
2
Wisconsin State Legislature. Wisconsin Statutes 71.64 – Employers Required to Withhold
3
Wisconsin Department of Revenue. Application for Wisconsin Business Tax Registration
4
Wisconsin Department of Revenue. Business Tax Registration
5
Wisconsin Department of Revenue. Business Tax Online Registration
6
Wisconsin Department of Revenue. Wisconsin Form WT-4 Employee’s Wisconsin Withholding Exemption Certificate
7
Wisconsin Department of Workforce Development. Wisconsin New Hire Reporting
8
Wisconsin Department of Revenue. W-166 Withholding Tax Guide
9
Wisconsin State Legislature. Wisconsin Statutes 71.65 – Filing Returns or Reports
10
Wisconsin Department of Revenue. 2025 Wisconsin Form WT-7 Instructions
11
Wisconsin Department of Revenue. General Withholding Tax Questions
12
Wisconsin State Legislature. Wisconsin Statutes 71.83 – Penalties