Check our 2025 Tax Deadlines For C-Corp Startups or Click for your customized tax compliance calendar by startup hub
The most important tax deadlines in 2025 for C-Corporation (C-Corps) are the April 15th federal Form 1120 tax return, which can be extended to October 15th, and the March, June, September, and December Delaware Franchise estimated payments. See our detailed calendar below for other, important dates or download our ical to add the dates to your calendar.
Delaware Quarterly Estimated Franchise Tax. Pay 20% of your estimated annual amount (if annual amount expected to exceed $5,000).
Delaware Quarterly Estimated Franchise Tax, Pay 20% of estimated annual amount (if annual amount expected to exceed $5,000).
Click The Links To Learn More About These Filings And 2025 C-Corp Startup Tax Deadlines
Claim Research & Development Tax Credits on Form 941, and file annual Federal Unemployment Tax Act (FUTA) return on Form 940. Use our handy calculator to estimate your possible research and development tax credit.
Delaware Annual Franchise Report filing deadline. Your C-Corp startup will pay a minimum of $400, which increases if you have significant funding.
IRS 30-day automatic extension: provide Form 1095-B and Form 1095C to employees.
C Corp Form 1120 Tax Return due. The Federal Form 1120 is the U.S. Corporation Income Tax Return, which the IRS has companies use to report their income, losses, credits, etc., and to figure the income tax liability of the corporation. Can extend the deadline to Oct. 15. All C-Corp startups are required to file this Federal form by this deadline unless they file an extension.
Federal Quarterly Estimated Tax 1st installment (first quarter 2024).
File the R&D Tax Credit Form 6765 with your tax return. Can extend to October 15. We strongly recommend working with a qualified CPA to prepare this form in conjunction with your Form 1120 if you are a high-growth startup – if your company is going to be acquired by a major technology company, that company’s CFO will use a strong tax team to do due diligence on this.
Due date for C-Corp startup employees to make contributions to Individual Retirement Accounts (IRAs) for 2023 (Employee Benefits).
C-Corp startups can claim Research & Development Tax Credits on Form 941.
Delaware Quarterly Estimated Franchise Tax. Pay 40% of estimated annual amount (if annual amount expected to exceed $5,000).
Federal Quarterly Estimated Tax 2nd installment (second quarter 2024).
Claim Research & Development Tax Credits on Form 941 .
Delaware Quarterly Estimated Franchise Tax. Pay 20% of your estimated annual amount (if annual amount expected to exceed $5,000).
Federal Quarterly Estimated Tax 3rd installment (third quarter 2024).
C Corp Form 1120 Tax Return final due date for C-Corp startups if extension was filed.
Claim your Research & Development Tax Credits on Form 941.
Delaware Quarterly Estimated Franchise Tax, Pay 20% of estimated annual amount (if annual amount expected to exceed $5,000).
Federal Quarterly Estimated Tax 4th installment (fourth quarter 2024).
Note: The federal tax deadline in 2025 falls on April 15. The federal extension deadline for 2025 is October 15. When the tax deadline is on weekend or holiday, the deadline is moved to the next business day.
It’s important for founders to remember that even early-stage, just founded companies can have compliance and regulatory filing requirements. And it’s critical to keep your company in compliance so that you’re ready for a venture capital term sheet or M&A due diligence. You want to be make sure that your financials are in good shape and won’t delay that transaction. Plus any regulatory or compliance issues can generate penalties and paperwork – which are distractions you don’t need when you’re building a business.
To help you stay on track, here are the most important compliance deadlines for all small businesses, and startups in particular:
That’s a lot to remember, but keeping your startup compliant with taxes and fees is crucial to your success.
We have a more complete list above, but the most important corporate tax deadline for businesses in 2025 is the April 15th federal and state tax due date. C corporations also have estimated quarterly taxes due on April 15th, June 15th and September 15th for businesses and corporations. C-corps can file an extension with the IRS Form 7004.
Remember, even unprofitable startups need to follow these deadlines. The federal (and state) governments require filings even if your company has a loss.
The due date for filing Form 1120, the corporate income tax return, for most US corporations is April 15th, 2025. Corporations can also request an extension to file their Form 1120 until October 15th, 2025 by submitting Form 7004 to the Internal Revenue Service (IRS) by the original due date. The IRS is responsible for enforcing federal income tax laws and administering the tax system in the US.
C-Corp taxes are due on the 15th of April, which is the deadline for filing the C Corp Form 1120 Tax Return. However, it is important to note that this deadline can be extended to October 15th if an extension is filed.
For businesses generating taxable income, quarterly estimated tax payments are generally due for businesses four times a year:
Note that the actual date may move slightly based on federal holidays and weekends, and that businesses with different tax fiscal year ends may have different dates. Additionally, state and local governments may be different, so always work with a qualified tax CPA.
The above calendar shows the most important Federal Tax deadlines for 2025 (it also includes some dates for Delaware C-Corps, our CPA firm’s particular client focus). The most important federal tax deadlines to focus on for C-Corps include sending W2s to employees and 1099s to contractors, the Federal & State Returns/Filings, R&D Credits and other tax credit deadlines.
The last day for a startup to file taxes is the due date for filing a Form 1120, which is the tax return form used by C-corporations (which most startups should be) to report their income, gains, losses, deductions, and credits to the (IRS), is generally the 15th day of the fourth month following the end of the corporation’s tax year. This is typically April 15th. For example, if a C-corporation has a calendar year tax year (January 1 to December 31), the due date for its Form 1120 tax return would be April 15. If a C-corporation has a fiscal year tax year (a 12-month period ending on the last day of any month except December), the due date for its Form 1120 tax return would be the 15th day of the fourth month following the end of the fiscal year.
If the due date for filing a tax return falls on a Saturday, Sunday, or legal holiday, the due date is moved to the next business day. This means that if April 15 falls on a weekend or legal holiday, the due date for filing the tax return would be the next business day.
If a C-corporation is unable to file its Form 1120 tax return by the due date, it can request an extension of time to file. To obtain an extension, the corporation must file Form 7004, Application for Automatic Extension of Time To File Certain Business Income Tax, Information, and Other Returns, by the original due date of the return. The extension will generally allow the corporation to file its tax return up to six months after the original due date.
The last day to file taxes in 2025 for C-Corporation (C-Corps) for the tax year 2024 is April 15th, which can be extended to October 15th. Additionally, there are March, June, September, and December Delaware Franchise estimated payments that should be paid and filed for companies reporting profits; talk to your tax CPA to see if you need to file anything on these dates.
An estimate of your payment is due on April 15, 2025. The last day that you can extend C-Corp tax filings until in 2025 will be October 15, 2025 (for the fiscal year ending December 31, 2024). Again, you have to file the extension by the original due date of April 15, 2025. Also note that you should pay an estimate of your 2024 amount due before April 15, or else you may face penalties and interest.
On average, one to three of our clients are acquired every month, and we what questions that the accounting firms at big, public companies are going to ask (you can access our free due diligence checklist here). Compliance is a big one! Don’t let a life-changing transaction get sidetracked by these types of issues. Of course, we recommend working with an experienced CPA like Kruze - talk to us now.
2024 startup tax deadlines are supplied for reference purposes only, and should not be used when making decisions in 2025 or beyond. Always consult your tax professional, and see our disclaimer below.
Click The Links To Learn More About These Filings And 2024 C-Corp Startup Tax Deadlines
Federal Quarterly Estimated Tax 4th installment (fourth quarter 2023).
C-Corp startups should send 1099s to contractors. Send W2s to employees and e-file 1099-MISC for non-employee compensation with the IRS. Or file Form 8809 for a 30-day extension to file W2s and 1099-MISC for non-employee compensation.
Claim Research & Development Tax Credits on Form 941, and file annual Federal Unemployment Tax Act (FUTA) return on Form 940. Use our handy calculator to estimate your possible research and development tax credit.
IRS 30-day automatic extension: provide Form 1095-B and Form 1095C to employees.
Delaware Annual Franchise Report filing deadline. Your C-Corp startup will pay a minimum of $400, which increases if you have significant funding.
Due date for C-Corp startup employees to make contributions to Individual Retirement Accounts (IRAs) for 2023 (Employee Benefits).
File the R&D Tax Credit Form 6765 with your tax return. Can extend to October 15. We strongly recommend working with a qualified CPA to prepare this form in conjunction with your Form 1120 if you are a high-growth startup – if your company is going to be acquired by a major technology company, that company’s CFO will use a strong tax team to do due diligence on this.
Federal Quarterly Estimated Tax 1st installment (first quarter 2024).
C Corp Form 1120 Tax Return due. The Federal Form 1120 is the U.S. Corporation Income Tax Return, which the IRS has companies use to report their income, losses, credits, etc., and to figure the income tax liability of the corporation. Can extend the deadline to Oct. 15. All C-Corp startups are required to file this Federal form by this deadline unless they file an extension.
C-Corp startups can claim Research & Development Tax Credits on Form 941.
Delaware Quarterly Estimated Franchise Tax. Pay 40% of estimated annual amount (if annual amount expected to exceed $5,000).
Federal Quarterly Estimated Tax 2nd installment (second quarter 2024).
Claim Research & Development Tax Credits on Form 941 .
Delaware Quarterly Estimated Franchise Tax. Pay 20% of your estimated annual amount (if annual amount expected to exceed $5,000).
Federal Quarterly Estimated Tax 3rd installment (third quarter 2024).
C Corp Form 1120 Tax Return final due date for C-Corp startups if extension was filed.
Claim your Research & Development Tax Credits on Form 941.
Delaware Quarterly Estimated Franchise Tax, Pay 20% of estimated annual amount (if annual amount expected to exceed $5,000).
View tax compliance dates for Austin, Boston, New York City, Palo Alto, San Francisco, Santa Monica, Seattle, Washington DC, Atlanta, Salt Lake City, Mountain View, Chicago, Dallas, Miami, and San Jose
How Much Does a Startup Tax Return Cost? Try Kruze Consulting's Tax Preparation Pricing Tool.
How much can your startup save in payroll taxes? Estimate your R&D tax credit using our free calculator.
Every startup is different and so are its tax compliance needs. This is only a guideline. Please consult your tax professional. IRS Circular 230 Disclaimer: To ensure compliance with IRS Circular 230, any U.S. federal tax advice provided in this communication is not intended or written to be used, and it cannot be used by the recipient or any other taxpayer for the purpose of avoiding tax penalties that may be imposed on the recipient or any other taxpayer. Copyright © Kruze Consulting
Check our 2025 Tax Deadlines For C-Corp Startups or Click for your customized tax compliance calendar by startup hub
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