Laid Off in Illinois: How Severance Cuts Your $578/wk UI

Marcus, a 41-year-old single filer in Chicago, earned $90,000 as a logistics manager before his employer cut 40 jobs. His package: 12 weeks’ severance — $22,500 gross — plus accrued vacation. His employer has 320 employees. Marcus assumed he had to burn through the severance first, then file for unemployment. That assumption would have cost him roughly $7,000.

In Illinois, severance and unemployment are not mutually exclusive. He can collect the IDES weekly maximum of about $578 starting the week he separates and keep every dollar of his $22,500 severance. The decision is not whether to file — it is to file now. This article walks the exact Illinois math: the unemployment offset rule, the WARN Act notice he was owed, and how a $22,500 lump sum is taxed at the flat 4.95% state rate.

The core rule: Illinois does not offset severance against UI

This is the single most important fact for a laid-off Illinois worker, and it is the opposite of what happens in several other states. The Illinois Department of Employment Security (IDES) does not count a severance lump sum as “wages” that get allocated to future weeks and push back your benefits.

Compare three states a worker might face:

Because Illinois falls in the first row, the timing answer is unambiguous: file the week your employment ends. Every week you wait is a week of benefits you forfeit — up to $578 each. Waiting 12 weeks for severance to “run out” (the way you would in Texas) would forfeit roughly $578 × 12 = $6,936 for no reason.

The one-week waiting period

Illinois imposes a single unpaid waiting week at the start of a claim. You still file that week — you certify for it — but it is not paid. Filing immediately starts that clock so your first paid week arrives sooner. This is another reason delay only hurts you.

What the $578 weekly maximum actually means

The IDES weekly benefit amount is calculated as roughly 47% of your average weekly wage in the two highest-earning quarters of your base period, capped at a statewide maximum. For 2026, that maximum is approximately $578/week for a claimant with no dependents (the cap is higher with a dependent spouse or children).

On a $90,000 salary, Marcus’s average weekly wage is about $1,731. Forty-seven percent of that is roughly $814 — well above the cap — so he receives the maximum $578. Benefits run up to 26 weeks in a benefit year, making his maximum potential UI payout:

One caveat: unemployment benefits are taxable income. They are not subject to the 4.95% Illinois rate the same way wages are withheld, but you will report them federally and on your Illinois return. You can elect 10% federal withholding on your UI checks — do it, so you are not surprised in April.

How a $22,500 severance lump sum is taxed

Severance is supplemental wages. The federal flat supplemental withholding rate is 22% on amounts up to $1 million (37% above that), under the supplemental-wage withholding rules at IRC § 3402 and 26 CFR § 31.3402(g)-1. Illinois layers its flat 4.95% rate on top (35 ILCS 5/201) — the state has no brackets, so every dollar of wage income is taxed at the same rate.

Note the FICA line. Severance is still subject to Social Security (6.2% up to the $181,800 wage base for 2026 under IRC § 3121) and Medicare (1.45%) — a detail many workers forget when they budget around a “$22,500” check that actually lands closer to $14,700.

On Marcus’s actual marginal federal rate: with $90,000 in salary already earned plus $22,500 severance, his top dollars sit in the 22% federal bracket (single: $48,476–$103,350 for 2026). The 22% flat supplemental withholding happens to match his real marginal rate closely, so he is unlikely to owe a large federal balance on the severance itself — the gap to watch is the unemployment income, which is often under-withheld.

One planning move blunts the supplemental-withholding sting: if the lump sum lands in a year when your total income will be lower than usual (you were laid off mid-year, so your final W-2 may be well under a full $90,000), the 22% flat withholding can over-withhold relative to your real effective rate. You do not change the withholding — the employer is required to use the supplemental method — but you recover any excess as a refund when you file. That refund is real money; just do not count on it as available cash during your job search.

Severance vs. vacation payout: the one exception to watch

The “no offset” rule applies to true severance — a payment for past service, separate from earned wages. There is one category that behaves differently in some IDES determinations: accrued vacation or holiday pay paid out at separation.

Where severance is unambiguously a past-service payment, a vacation payout can be treated as wages allocated to the period it covers, which can reduce or delay benefits for the weeks it is attributed to. The practical takeaways:

• Report both honestly on your IDES certification. Underreporting separation pay is how overpayment notices — and clawbacks — happen.
• Ask your employer how each line is coded. A check labeled “severance” and a check labeled “vacation payout” can be treated differently by IDES even if they hit your account the same day.
• The vacation payout does not block your claim — at most it may affect the specific week it is allocated to. Your 26-week clock and your $578 weekly amount are intact.

For Marcus, his $22,500 is coded as severance, so it is fully outside the offset. His accrued vacation — if paid as a separate line — gets reported but does not derail the claim.

File now vs. file later: the side-by-side

Here is the decision in dollars. Marcus collects the same $22,500 severance either way. The only variable is whether he files for IDES the week he separates or waits 12 weeks for the severance to “run out” (the Texas instinct, wrong for Illinois):

The benefit year is a fixed 52-week window that starts when you file. Push your filing date back 12 weeks and you compress the weeks in which you can actually draw benefits before the rest of your job search eats into that window — or before you find work and stop claiming. The clean answer: filing immediately is worth roughly $6,900 versus waiting, with zero downside, because the severance is untouched either way.

The Illinois WARN Act: were you owed 60 days’ notice?

The Illinois WARN Act is broader than the federal WARN Act. Federal WARN covers employers with 100+ employees. The Illinois version reaches down to employers with 75 or more full-time workers and requires 60 calendar days’ advance written notice of a mass layoff or plant closing.

Illinois WARN is triggered by any of these:

• 25 or more full-time employees laid off, if they make up at least one-third of the workforce at a single site; or
• 250 or more full-time employees laid off, regardless of percentage; or
• A plant closing affecting 50+ employees.

Marcus’s employer has 320 workers and cut 40 of them. If those 40 were at least one-third of his site, or if the total crossed the site-level threshold, the company owed 60 days’ notice. If it failed to give that notice, the remedy is back pay and benefits for each day of the shortfall, up to 60 days. A worker given only 14 days’ notice could be owed roughly 46 days of pay — potentially more than the entire severance package. This is a claim worth checking before you sign a release.

What most people miss: signing the release too fast

The costly mistake is not the tax math — it is the severance agreement. Three things get overlooked:

1. The release may waive your WARN claim. If the company shorted you on the 60-day notice, the back-pay you are owed under the Illinois WARN Act can exceed the severance. Signing the standard release often waives that claim. If you suspect a WARN violation, get the agreement reviewed before signing — the 60-day back-pay can be the larger number.
2. Workers think severance blocks unemployment. It does not in Illinois. The myth that you must “use up” severance first is true in Texas and several other states — not here. Filing late is pure forfeited benefit.
3. The over-21 / 7-day window. If you are 40 or older and the layoff is a group termination, federal law (the OWBPA under the ADEA) usually gives you 45 days to consider the agreement and 7 days to revoke after signing. You are not obligated to sign on the spot. Use the time to check the WARN math and the UI timing.

The Illinois playbook, in order

1. File for IDES benefits the week you separate — before severance, not after. There is no offset; waiting forfeits up to $578/week.
2. Elect 10% federal withholding on your UI checks so the taxable benefits do not create an April surprise.
3. Check the WARN math — 75+ employee employer, 60-day notice. If you got less, you may be owed back pay that exceeds your severance.
4. Budget on the net, not the gross. A $22,500 severance lands near $14,700 after federal supplemental withholding (22%), Illinois 4.95%, and FICA (7.65%).
5. Use the consideration window if you are 40+ in a group layoff — up to 45 days to decide, 7 to revoke.

The decision lever

For an Illinois worker, the lever that moves the most money is filing timing, not tax optimization. Because IDES does not offset severance, the worker who files the week of separation collects up to $15,028 in unemployment on top of the full severance — while the worker who waits for severance to run out collects the same severance and thousands less in benefits. The second lever is the WARN claim: confirm you received your 60 days’ notice before you sign away the right to challenge it. Pull your separation letter, count the calendar days, and file your IDES claim this week.