Tax
Form 1120 (C-corp Return)
Quick definition
Annual income tax return for C-corporations. Due April 15 (or 15th day of 4th month after fiscal year end) for calendar-year filers.
Form 1120 is the standard corporate income tax return for C-corps. Reports gross income, deductions, taxable income, and tax liability. Due April 15 for calendar-year filers; 6-month automatic extension available via Form 7004 (extended due date October 15). Most growth-stage startups file 1120 even at a loss because of net-operating-loss carryforward planning and to maintain good standing.
Related tax terms
R&D Tax Credit
Federal credit for qualified research expenses, usable against payroll tax by startups.
Delaware Franchise Tax
Annual tax for Delaware corporations, often quoted wildly too high if calculated incorrectly.
Nexus (Sales Tax)
The connection with a state that triggers a tax-collection obligation.
QSBS (Qualified Small Business Stock)
Tax exemption for gains on qualifying startup stock held 5+ years.
See this in action
Insights and tools where Form 1120 (C-corp Return) shows up.
Frequently asked questions
- What is Form 1120 (C-corp Return)?
- Form 1120 is the standard corporate income tax return for C-corps. Reports gross income, deductions, taxable income, and tax liability. Due April 15 for calendar-year filers; 6-month automatic extension available via Form 7004 (extended due date October 15). Most growth-stage startups file 1120 even at a loss because of net-operating-loss carryforward planning and to maintain good standing.
- Why is Form 1120 (C-corp Return) important for startups?
- Form 1120 (C-corp Return) is a tax concept that matters for startup founders because it directly affects fundraising readiness, financial decision-making, or operational discipline at the stage where mistakes are expensive to undo. Founders who understand it have a meaningfully easier time in diligence, board meetings, and investor conversations.
- What category does Form 1120 (C-corp Return) belong to?
- Form 1120 (C-corp Return) is a Tax term in the StartupCFO finance glossary — alongside other tax concepts that founders, CFOs, and accountants use in daily startup operations and reporting.
- Where can I learn more about Form 1120 (C-corp Return)?
- Beyond this definition, see the related tax terms below, or explore StartupCFO's insights and tools that put Form 1120 (C-corp Return) in context. For specific situations, talk to a fractional CFO who can walk through your numbers.
Got a finance question that needs more than a definition?
Talk to a real CFO. 30 minutes, no contract, free.
