Form 1120, officially called the U.S. Corporation Income Tax Return, is used by C-Corporations to report:
Income
Deductions
Tax credits
Estimated payments
Taxes owed or refund due
If you’ve formed a Delaware C-Corp startup, even without revenue, you're required to file.
You must file Form 1120 if:
You formed a C-Corp in any U.S. state (including Delaware)
Your company has income, expenses, or capital activity
Your startup operates on a calendar year (January–December)
💡 Foreign founders: You may also need to file Form 5472 if your C-Corp has foreign ownership.
This is the deadline for most startups using a calendar tax year (Jan 1–Dec 31).
🛑 Missed it? You can file an extension using Form 7004, but any taxes owed must still be paid by April 15.
🔗 Learn more: Form 7004: How to File a C-Corp Tax Extension
To file Form 1120, gather:
Your EIN (Employer Identification Number)
Your NAICS business code
Financials: Income, expenses, P&L, balance sheet
Capital contributions / equity grants
Any prior-year return (if applicable)
You can’t file Form 1120 directly on IRS.gov
Here’s how to do it:
Use an IRS-Authorized e-File Provider
(e.g., TaxBandits, Drake, ProConnect)
Hire a CPA or Tax Firm
Best if you’ve raised VC or need strategic help
Use TaxHero AI
Built for early-stage Delaware startups, TaxHero helps you:
Auto-track deadlines
Generate Form 1120
Stay compliant with IRS and Delaware
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🔗 Related: Startup Tax Checklist: Are You Ready for April 15?
Penalties for late Form 1120 filings can include:
5% of unpaid taxes per month (up to 25%)
Loss of good standing with Delaware
IRS scrutiny in future fundraising or audits
Even if your startup made $0, the IRS and Delaware Franchise Tax rules still expect a return.
Use available Startup Tax Deductions to lower your bill:
Up to $5,000 in startup costs
Salaries, marketing, software
R&D expenses (get the credit)
Founder's 83(b) election (avoid equity tax traps)
Form 1120 is just one piece of your 2025 filing puzzle. You may also need to:
Pay estimated taxes quarterly
Pay your Delaware Franchise Tax by March 1
🔗 Check the full 2025 Startup Tax Calendar
Or get your personal Tax Calendar in seconds for free: https://taxhero.vc/checkin
| Step | What to Do |
|---|---|
| Deadline | April 15, 2025 |
| Extension | File Form 7004 if needed |
| How to file | Through e-file provider, CPA, or TaxHero AI |
| What you need | EIN, income, expenses, equity details |
| Why it matters | IRS penalties, investor compliance, audits |
TaxHero AI helps early-stage Delaware C-Corps:
Auto-track IRS + Delaware deadlines (free calendar here: https://taxhero.vc/checkin )
File Form 1120 + Franchise Tax
Stay 100% compliant (no CPA required)
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