Most startup tax deadlines are boring, which is exactly why they get missed. The 2027 calendar looks like 2026, but the dates move: January 31 and February 28 both land on Sundays, and the One Big Beautiful Bill Act changed the 1099 thresholds. Copy last year's calendar forward and you will be wrong in at least three places.
This guide covers the startup tax deadlines 2027 brings for a typical calendar-year Delaware C-corp with employees and contractors. If you are looking for obligations that fell due during 2026, our 2026 startup tax deadlines calendar remains the reference for that year. Everything below has been re-derived for 2027.
How Weekend and Holiday Shifts Work in 2027
The IRS rule is simple: when a due date falls on a Saturday, Sunday or legal holiday in the District of Columbia, the deadline moves to the next business day. The IRS draft of Publication 509 for 2027 lists the legal holidays it uses, and three of them matter for startups:
- Washington's Birthday, Monday, February 15, 2027. This pushes the February 15 recipient deadline for certain 1099-MISC boxes to February 16.
- DC Emancipation Day, Friday, April 16, 2027. In some years this holiday pushes Tax Day to the 17th or 18th. In 2027 it falls the day after April 15, so the April 15 deadline stays on Thursday, April 15.
- Independence Day observed, Monday, July 5, 2027. Not a filing date for most startups, but it can affect payroll deposit timing.
The weekend shifts that matter most:
- January 31, 2027 is a Sunday. W-2s, 1099-NEC forms, Form 941 for Q4 2026 and Form 940 all move to Monday, February 1, 2027.
- February 28, 2027 is a Sunday. Paper 1099-MISC filings move to Monday, March 1, 2027.
- July 31, 2027 is a Saturday. The Q2 Form 941 moves to Monday, August 2, 2027.
- October 31, 2027 is a Sunday. The Q3 Form 941 moves to Monday, November 1, 2027.
Delaware follows its own rules, but March 1, 2027 is a Monday, so the franchise tax deadline does not move.
The 2027 Startup Tax Calendar at a Glance
Every date assumes a calendar-year C-corp. Penalties are summarized; read the sections below for detail.
| Date | Form or obligation | Who files | Penalty if missed |
|---|---|---|---|
| Jan 15, 2027 | Form 1040-ES, Q4 2026 personal estimate | Founders with non-wage income | Underpayment interest (7% for Q4 2026) |
| Feb 1, 2027 | Form W-2 to employees and W-2/W-3 to SSA | Any company with 2026 payroll | Information return penalties, $60 to $340 per form |
| Feb 1, 2027 | Form 1099-NEC to recipients and IRS | Payers of $2,000+ to contractors in 2026 | $60 to $340 per form; $690 intentional disregard |
| Feb 1, 2027 | Form 941 (Q4 2026) and Form 940 (2026) | Employers | Failure-to-file and failure-to-deposit penalties |
| Feb 16, 2027 | 1099-MISC to recipients (box 8 and box 10 only) | Payers of attorney proceeds or substitute payments | $60 to $340 per form |
| Mar 1, 2027 | Delaware annual report and franchise tax | Every Delaware corporation | $200 plus 1.5% monthly interest |
| Mar 1, 2027 | Paper 1099-MISC and Form 1096 to IRS | Paper filers only | $60 to $340 per form |
| Mar 31, 2027 | Electronic 1099-MISC to IRS | E-filers | $60 to $340 per form |
| Apr 15, 2027 | Form 1120 or Form 7004 extension, with Form 5472 and Form 6765 if applicable | C-corps | 5% per month of unpaid tax, up to 25%; $25,000 per Form 5472 |
| Apr 15, 2027 | Q1 2027 corporate estimate | C-corps expecting tax | Underpayment interest (Form 2220) |
| Apr 30, 2027 | Form 941, Q1 2027 | Employers | Failure-to-file and deposit penalties |
| Jun 15, 2027 | Q2 2027 corporate estimate | C-corps | Underpayment interest |
| Aug 2, 2027 | Form 941, Q2 2027 | Employers | Failure-to-file and deposit penalties |
| Sep 15, 2027 | Q3 2027 corporate estimate | C-corps | Underpayment interest |
| Oct 15, 2027 | Extended Form 1120 | C-corps that filed Form 7004 | 5% per month of unpaid tax, up to 25% |
| Nov 1, 2027 | Form 941, Q3 2027 | Employers | Failure-to-file and deposit penalties |
| Dec 15, 2027 | Q4 2027 corporate estimate | C-corps | Underpayment interest |
| Rolling | 83(b) election within 30 days of grant | Founders and employees receiving restricted stock | Election lost; no late relief |
January 2027
January 15 (Friday): Q4 2026 personal estimated tax, Form 1040-ES. This is a founder deadline, not a corporate one. If you have income outside payroll withholding, such as consulting income, a secondary sale, or interest on a large cash balance, the final 2026 installment is due here. The corporate Q4 2026 estimate was already due December 15, 2026.
The IRS underpayment rate is 7 percent for the fourth quarter of 2026 and resets quarterly. Check the IRS quarterly interest rate page for the first quarter 2027 rate once it is announced.
January: close December. Accurate W-2s, 1099s, a Delaware gross assets figure and an R&D study all depend on closed December books.
February 2027
February 1 (Monday): W-2s to employees and to the Social Security Administration. Employee copies and the Form W-3 with Copy A are due the same day. Payroll providers file automatically, but only for people they know about; founders paid outside payroll are the usual gap.
February 1 (Monday): Form 1099-NEC to contractors and to the IRS. This is the 1099 deadline 2027 founders search for, and it is where the law changed. Under the One Big Beautiful Bill Act, the threshold for reporting nonemployee compensation rose from $600 to $2,000 for payments made after December 31, 2025. The IRS 1099-MISC and 1099-NEC instructions confirm that the $2,000 threshold applies to 2026 payments and may be adjusted for inflation beginning in calendar year 2027. So the forms you file in early 2027, which report 2026 payments, use $2,000.
Three details founders get wrong:
- Not every 1099 threshold moved. Royalties are still reported at $10, and gross proceeds paid to an attorney (Form 1099-MISC box 10) are still reported at $600.
- The threshold is per payee for the year, not per invoice. A contractor paid $900 four times crosses $2,000.
- Card payments are excluded. Payments made through a credit card or a payment network are reported by the processor on Form 1099-K, not by you.
Both copies of the 1099-NEC are due February 1. There is no later paper deadline for the NEC. Penalties for information returns due in 2027 are $60 per form if filed within 30 days, $130 if filed after 30 days but by August 1, $340 after August 1 or never, and $690 per form with no annual cap for intentional disregard.
If your company files 10 or more information returns in total across all types (W-2s and 1099s count together), you must file electronically.
February 1 (Monday): Form 941 for Q4 2026 and Form 940 for 2026. If all tax was deposited on time and in full, you have until February 10 to file. Confirm your payroll provider filed both, especially after a mid-year switch.
February 16 (Tuesday): Recipient copies of certain 1099-MISC forms. The February 15 date for box 8 and box 10 statements moves because of Washington's Birthday. Most startups only hit this after paying attorney gross proceeds, such as a settlement.
March 2027
March 1 (Monday): Delaware franchise tax and annual report. This is the Delaware franchise tax deadline 2027 imposes on every domestic Delaware corporation, revenue or not. The Delaware Division of Corporations sets the rules:
- Two calculation methods. The authorized shares method has a $175 minimum. The assumed par value capital method has a $400 minimum. The maximum under either is $200,000, or $250,000 for corporations identified as Large Corporate Filers.
- Annual report fee. $50 for a non-exempt domestic corporation.
- Late penalty. $200 for not filing a completed annual report by March 1, plus interest of 1.5 percent per month on unpaid tax.
The trap is the same every year. Delaware's notice usually shows tax calculated under the authorized shares method, and for a startup with 10 million or more authorized shares that number can be tens of thousands of dollars. The assumed par value capital method uses your total gross assets and issued shares, and for most early-stage companies it produces a bill at or near the $400 minimum. Run both before you pay. Our Delaware franchise tax calculator does the math in about a minute.
You need two numbers from your December 31, 2026 books: total gross assets (the figure that will appear on your Form 1120 Schedule L) and issued shares. This is another reason the January close matters.
March 1 (Monday): Paper 1099-MISC and Form 1096. February 28 is a Sunday, so paper filers get until March 1. Electronic filers of 1099-MISC have until March 31 (Wednesday). Neither date applies to the 1099-NEC, which was due February 1.
March 15 (Monday): S-corp and partnership returns. Forms 1120-S and 1065 are due. Most venture-backed C-corps do not file these, but founders with a holding LLC or an SPV interest may.
April 2027
April 15 (Thursday): Form 1120 or Form 7004. The C-corp return for calendar year 2026 is due. Filing Form 7004 by April 15 extends the filing deadline six months to October 15, 2027. The extension does not extend the time to pay; any tax owed is still due April 15. Filing late without an extension triggers the failure-to-file penalty of 5 percent of unpaid tax per month, up to 25 percent. For returns more than 60 days late there is also a minimum penalty, $525 for returns due in 2026 and indexed for inflation, so confirm the 2027 figure in the current Form 1120 instructions. An unprofitable startup with zero tax due still has to file.
April 15: attachments that ride with the 1120. Several of the most expensive obligations of the year are not standalone deadlines; they are attachments due with the return, including extensions:
- Form 5472 for foreign-owned companies. A US corporation that is 25 percent or more foreign-owned, and that had reportable transactions with a foreign or related party, attaches Form 5472. The penalty for failing to file, or filing a substantially incomplete form, is $25,000 per form, with an additional $25,000 for each 30 days the failure continues after 90 days from IRS notice. Our Form 5472 guide covers who files and what counts as a reportable transaction.
- Form 6765 for the R&D credit. The research credit is claimed on Form 6765, attached to the 1120.
April 15: the R&D payroll tax election. A qualified small business, meaning gross receipts under $5 million for the year and no gross receipts before the five-year period ending with that year, can elect to apply up to $500,000 of research credit against payroll taxes instead of income tax. For pre-revenue startups this is the only way the credit produces cash. The election must be made on a timely filed original return, including extensions. File the 2026 return late and the 2026 payroll election is gone. Once the return is filed, the credit is claimed against payroll tax on Form 8974 with your Form 941, starting with the first quarter that begins after the return is filed. Our R&D tax credit estimator gives a first-pass number.
Two R&D items to plan for in 2027:
- Form 6765 Section G. The IRS instructions made the business component detail in Section G optional for tax years beginning before 2026. For tax years beginning in 2026 and later it becomes required, with exceptions for smaller filers. Check the current instructions when preparing the 2026 return, and start collecting project-level documentation now rather than at filing time.
- Section 174A. The One Big Beautiful Bill Act restored immediate expensing of domestic research costs for tax years beginning after December 31, 2024. Foreign research is still amortized over 15 years.
April 15: Q1 2027 corporate estimated tax. The first 2027 installment is due. More on estimates below.
April 15: founder personal returns. Form 1040 for 2026 is due the same day, along with the Q1 2027 personal estimate. Most founders with K-1s or equity events extend with Form 4868.
April 30 (Friday): Form 941 for Q1 2027.
June to December 2027
June 15 (Tuesday): Q2 2027 corporate estimate.
June 30: Delaware annual report for foreign corporations. This applies only to companies formed outside Delaware that are registered there. A domestic Delaware corporation does not get a second chance in June; its penalties have been accruing since March 1.
August 2 (Monday): Form 941 for Q2 2027. July 31 is a Saturday.
September 15 (Wednesday): Q3 2027 corporate estimate.
October 15 (Friday): extended Form 1120. If you filed Form 7004 in April, this is the final deadline. It is also the last day to make elections that must be made on a timely filed return, including the R&D payroll election. Do not treat it as soft.
November 1 (Monday): Form 941 for Q3 2027. October 31 is a Sunday.
December 15 (Wednesday): Q4 2027 corporate estimate. The last corporate installment of the year.
Corporate Estimated Taxes in 2027
C-corps pay estimates on the 15th day of the 4th, 6th, 9th and 12th months of the tax year: April 15, June 15, September 15 and December 15 in 2027, none of which moves this year. There is no corporate January payment.
You generally owe estimates if you expect $500 or more of tax for the year. Loss-making startups often owe nothing, but a profitable year or a large interest income balance changes that quickly. Shortfalls are computed on Form 2220 at the IRS underpayment rate.
Rolling and Event-Driven Deadlines
83(b) elections: 30 days, no exceptions. When a founder or early employee receives restricted stock subject to vesting, they have 30 days from the grant date to file an 83(b) election with the IRS. If day 30 falls on a weekend or holiday, it moves to the next business day. The IRS created Form 15620 for the purpose, though a written statement meeting the regulations also works. As of this writing, the IRS instructions direct taxpayers to mail it, so send it by certified mail and keep the receipt. A missed 83(b) cannot be fixed after the fact. Our guide on how to file an 83(b) election walks through it.
BOI reporting: no longer required for US companies. In March 2025, FinCEN issued an interim final rule narrowing the Corporate Transparency Act's reporting requirement to entities formed under foreign law and registered to do business in a US state. A US-formed Delaware C-corp is exempt and does not need to file or update a BOI report. FinCEN has since issued a final rule making the exemption permanent. If your company is a foreign entity registered in a US state, it is still a reporting company, so confirm current deadlines on FinCEN's BOI page.
State franchise taxes and annual reports. Delaware is not your only state. Registering to do business where you have employees or an office usually brings an annual report and, in many states, a franchise or minimum tax. California's $800 minimum franchise tax applies to corporations doing business there whether or not they are profitable. New York, Texas, Massachusetts and others have their own filings and calendars. Track each state separately; a missed annual report can lead to loss of good standing, which shows up at exactly the wrong moment in diligence.
State payroll, income and sales tax. Each state with an employee generally means withholding and unemployment filings, often quarterly, plus a state income tax return. SaaS is also taxable in many states once you cross economic nexus thresholds. For a remote team that can mean a dozen calendars.
The Gotchas That Cost Real Money
Ranked roughly by how much damage they do:
- Paying Delaware under the authorized shares method. Always recalculate under assumed par value capital.
- Losing the R&D payroll election. A late 1120 forfeits up to $500,000 of payroll offset for the year.
- Skipping Form 5472. $25,000 per form, even when no tax is owed.
- Skipping W-9s because of the new threshold. Reporting at $600 is harmless overreporting; not collecting W-9s at all is the real risk.
- Missing an 83(b). The tax cost lands years later, when vested shares are worth far more.
- Assuming the extension extends payment. Form 7004 buys time to file, not to pay.
Staying Ahead of the 2027 Calendar
A calendar is only useful if someone owns it. At StartupCFO, deadline tracking across all 50 states is included in every plan, and every plan includes a 50 percent discount on preparation of one federal and one state return. Filing fees and additional states are add-ons. If you run this in-house, our free startup tax compliance calendar is a good starting point.
Whatever you use, put these dates on a shared calendar now and assign an owner to each. Most missed deadlines are bookkeeping problems that surface as tax problems.
