An SUI number is the account number a state workforce agency assigns to an employer that owes state unemployment insurance tax. It ties your business to everything the state tracks about you as an employer: tax payments, quarterly wage reports, and any unemployment claims filed by former workers. Because every state runs its own unemployment insurance program, a business with employees in three states needs three separate SUI numbers, one from each state’s agency.
Who Has to Get One
Federal law defines an employer, for unemployment tax purposes, as a business that paid $1,500 or more in wages during any calendar quarter or had at least one employee for some part of a day in 20 different weeks during the current or prior year.1Internal Revenue Service. Topic No. 759, Form 940 – Employers Annual Federal Unemployment Tax Most states adopted identical or very similar thresholds, so if you owe federal unemployment tax you almost certainly owe state tax too. Some states set the bar lower, meaning you can be liable for state unemployment tax before you’re liable federally.
A few categories of employers follow different rules. Agricultural employers in many states become liable when their payroll hits $20,000 in a quarter or they employ 10 or more workers for 20 weeks. Domestic employers often trigger liability at a lower wage threshold, sometimes as little as $1,000 in a quarter. Nonprofits also have their own path. The specifics vary, but the pattern is the same: cross the threshold, register for an SUI number.
Independent Contractors Don’t Count
You only cover workers who qualify as employees. Independent contractors are excluded from unemployment insurance, and their pay doesn’t go on quarterly wage reports. States look at the actual working relationship, not the label on a contract. Many states apply some version of the “ABC test,” which presumes a worker is an employee unless the business can show the worker is free from the company’s control, performs work outside the company’s usual business, and operates an independently established trade or profession. Misclassifying an employee as a contractor can produce back taxes, penalties, and interest on every dollar of wages that should have been reported.
How to Register
You register through your state’s workforce or labor agency, not the IRS. Most states now offer online registration portals. You’ll typically need your federal Employer Identification Number, the business’s legal name and address, the entity type (LLC, corporation, sole proprietorship), and the date wages were first paid. States often also ask for your North American Industry Classification System code, the number of employees you expect to have, and whether you’re acquiring an existing business.
Get the EIN first. The IRS issues EINs to businesses that have employees or meet other filing requirements, and states generally require it on the SUI registration form.2Internal Revenue Service. Employer Identification Number If you don’t have one yet, you can apply online through the IRS and receive it immediately.
Once you register, the state assigns your SUI account number and notifies you of your initial tax rate. Keep the number accessible. You’ll need it on every quarterly filing, every tax payment, and every piece of correspondence with the agency. If you lose it, prior quarterly forms and state notices will have it, or you can call the agency directly.
Buying an existing business is a special case worth flagging before you close. Most states have successor liability rules that transfer some or all of the prior owner’s unemployment tax account (including the tax rate, account balance, and sometimes outstanding debts) to the new owner. Ask for the seller’s unemployment tax history before closing, because the rate you inherit can be much higher than the new-employer rate you’d otherwise get.
How Your Tax Rate Works
Your SUI rate isn’t fixed. It moves over time based on your claims history, a system called experience rating: the more benefits your former employees draw, the higher your rate climbs; fewer claims push it down.3U.S. Department of Labor. Experience Rating – Unemployment Insurance
New employers start at a default rate because they have no claims history yet. Starting rates vary widely by state, typically falling between about 1.0% and 3.5%. After you’ve been in the system for a minimum period (usually three years), the state recalculates your rate annually based on the claims charged to your account relative to your taxable payroll.
The Taxable Wage Base
You don’t pay SUI tax on an employee’s entire salary. Each state sets a taxable wage base, the maximum amount of each employee’s annual wages subject to the tax. For 2026, wage bases range from $7,000 in states like Arkansas, California, Florida, and Tennessee up to $78,200 in Washington. Once an employee’s year-to-date wages exceed the base, you stop owing SUI tax on their additional wages until the next calendar year.
The wage base is what makes rate comparisons across states misleading. A 3% rate in a state with a $7,000 base costs $210 per employee per year. That same 3% in Washington costs $2,346 per employee. Rate alone doesn’t tell you what you’ll owe.
Why Your SUI Number Affects Your Federal Tax
The federal Unemployment tax under FUTA runs 6.0% on the first $7,000 of wages per employee.4Office of the Law Revision Counsel. 26 USC 3301 – Rate of Tax Most employers never pay anywhere near that. If you pay your state unemployment tax on time, you get a credit of up to 5.4% against the federal rate, dropping your effective FUTA tax to 0.6%, or about $42 per employee per year on the $7,000 base.5Internal Revenue Service. Instructions for Form 940 (2025)
The phrase to notice is “on time.” If your state unemployment taxes aren’t paid by the federal deadline, you can lose part or all of that 5.4% credit. Separately, if your state has borrowed from the federal unemployment trust fund and hasn’t repaid within two years, employers in that state face an automatic credit reduction starting at 0.3% and growing 0.3% each additional year the loan is outstanding.6Internal Revenue Service. FUTA Credit Reduction Any credit reduction goes on Schedule A of Form 940.
What You Do With the Number
Your SUI number appears on nearly every interaction with the state workforce agency, and two uses come up every quarter.
First, wage reports. Each quarter you file a report listing every employee by name and Social Security number along with gross wages for the quarter. The state uses that data to decide benefit eligibility and amounts when a former employee files a claim. In most states, quarterly reports and payments share the same deadlines: April 30, July 31, October 31, and January 31 for the preceding quarter.
Second, claim responses. When a former employee files for benefits, the state sends you a notice identifying the claimant and asking for information about the separation. Benefits paid on valid claims get charged to your account and push your experience rating higher, so how you respond directly affects your future rate. If you believe the former employee doesn’t qualify, generally because they quit voluntarily or were fired for misconduct, you can protest. Deadlines are short, typically 10 to 15 days from the date the notice was mailed. Miss the deadline and the state decides without you. Even a single uncontested claim you could have won raises your tax rate for years.
Employees in More Than One State
If your employees work in different states, figuring out where to pay SUI tax follows a sequential test from the U.S. Department of Labor.7U.S. Department of Labor. UIPL No. 20-04 Attachment I – Localization of Work Provisions You start by asking whether the work is localized in one state (with any out-of-state work being temporary or incidental). If not, you look at the employee’s base of operations, then the state from which the work is directed and controlled, and finally the employee’s state of residence. Each step only applies if the earlier ones don’t resolve the question.
For remote workers, this usually lands on the employee’s home state, since that’s typically both where the work is localized and where the employee lives. You’ll need an SUI number in every state where you have covered employees, and you’ll file separate quarterly reports in each. Tracking different wage bases and rates across states by hand is where payroll software or a payroll provider earns its fee.
What It Costs to Get This Wrong
Failing to register, filing late, or not filing at all can stack up penalties fast. The specifics vary by state, but the common consequences include a civil penalty for registering late, late-filing penalties assessed either as a flat amount per employee or a percentage of tax owed, and interest on unpaid tax calculated monthly from the original due date.
The biggest hit is the one many employers underestimate: losing the FUTA credit. If state taxes go unpaid past the federal deadline, you can lose part or all of the 5.4% credit, effectively multiplying your federal unemployment tax liability by up to ten times.5Internal Revenue Service. Instructions for Form 940 (2025) A business with 50 employees paying tax on the $7,000 base owes $2,100 in FUTA at the normal 0.6% net rate. Lose the full credit and the same business owes $21,000 at the full 6.0%. Keeping state filings current is the cheapest way to avoid it.
How the SUI Number Differs From Your Other IDs
Employers juggle several identification numbers, and mixing them up causes rejected filings and misapplied payments. Your EIN is a federal number issued by the IRS for all federal tax purposes, including income tax withholding, FICA, and FUTA.2Internal Revenue Service. Employer Identification Number Your SUI number is state-issued and used only for state unemployment insurance filings. Some states also assign a separate state tax identification number for income tax withholding or sales tax, which is a different number entirely.
The EIN is your identity with the IRS. The SUI number is your identity with the state unemployment agency. A state tax ID is your identity with the state revenue department. They don’t substitute for each other, and running a single payroll can require all three.