Question 1

What's the most important tax deadline for Illinois LLCs?

Accepted Answer

For most Illinois LLC owners: federal quarterly estimated tax payments (April 15, June 15, Sept 15, Jan 15) + Illinois annual report (Prior to anniversary month — $75) + federal tax return (March 15 for partnerships/S-Corps, April 15 for SMLLC). Missing the annual report triggers admin dissolution.

Question 2

When are estimated tax payments due for Illinois LLCs?

Accepted Answer

Federal: quarterly on April 15, June 15, Sept 15, and Jan 15 of the following year. Pay at least 100% of last year's total tax (110% if AGI > $150K) or 90% of current year's liability to avoid underpayment penalties. Illinois state estimated tax varies — check Illinois Department of Revenue for state-specific quarterly dates.

Question 3

What's the Illinois state annual report deadline?

Accepted Answer

Prior to anniversary month — $75. Missing this deadline risks administrative dissolution of your LLC — which retroactively removes liability protection. Calendar it immediately after formation.

Question 4

When are federal LLC tax returns due?

Accepted Answer

Single-member LLC (disregarded): April 15 with personal 1040. Multi-member LLC (partnership): Form 1065 due March 15. S-Corp LLC: Form 1120-S due March 15. C-Corp LLC: Form 1120 due April 15. All except SMLLC can extend 6 months (to Sept 15 or Oct 15).

Question 5

What are the penalties for missing deadlines in Illinois?

Accepted Answer

Federal: 5%/month late filing (up to 25% of tax). State: varies — CA franchise fail = $800 + interest; FL late annual = $400; NY annual late = $9 penalty; TX franchise late = $50+. Admin dissolution risk if annual compliance missed 1-3 years.

Question 6

Does Illinois offer tax extensions?

Accepted Answer

Federal: automatic 6-month extension via Form 4868 (individual) or Form 7004 (entity). Illinois state extensions often require separate filing — most states grant 6 months but require a state extension form. Extensions extend filing time, NOT payment time — penalty interest still accrues on unpaid tax.

Illinois LLC Tax Deadlines Calendar

Federal LLC Tax Deadlines

Illinois State-Specific Deadlines

Illinois-Specific Notes

FAQ

What's the most important tax deadline for Illinois LLCs?

When are estimated tax payments due for Illinois LLCs?

What's the Illinois state annual report deadline?

When are federal LLC tax returns due?

What are the penalties for missing deadlines in Illinois?

Does Illinois offer tax extensions?

Estimate your Illinois quarterly taxes

Illinois LLC Tax Deadlines Calendar

Federal LLC Tax Deadlines

Illinois State-Specific Deadlines

Illinois-Specific Notes

FAQ

What's the most important tax deadline for Illinois LLCs?

When are estimated tax payments due for Illinois LLCs?

What's the Illinois state annual report deadline?

When are federal LLC tax returns due?

What are the penalties for missing deadlines in Illinois?

Does Illinois offer tax extensions?

Estimate your Illinois quarterly taxes