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Missing a tax deadline rarely costs you the most expensive item on its own. What costs you is what comes next: penalties stack, interest compounds, and one missed filing can trigger a series of additional notices and audits. Most small business owners do not miss deadlines because they do not care. They miss them because the calendar is full and nobody hands them a clean list.
This is that list. Every recurring federal tax deadline a US small business owner needs to watch in a calendar year, with the practical details around what gets filed, how to extend, and what happens if you miss it.
January is the busiest tax month for small business owners. Q4 estimated tax for the prior year, employee tax forms, and contractor 1099s all come due in the same window.
If a deadline falls on a Saturday, Sunday, or federal holiday, it shifts to the next business day. Plan for the actual day each year.
S-Corporations and partnerships have an earlier filing deadline than individuals and C-Corporations. The reason: their owners need K-1s before they can file their personal returns by April 15.
Late filing of an S-Corp return costs $245 per shareholder per month, capped at 12 months. A 3-shareholder S-Corp filed 4 months late owes a $2,940 penalty before any actual tax. Partnership penalties are structurally similar.
April 15 is the headline deadline most taxpayers know. For small business owners filing Schedule C or operating a C-Corporation, several filings stack on this date.
The extension extends the filing deadline only. Any tax owed is still due April 15. Pay the estimated balance with the extension request to avoid the late-payment penalty (0.5% per month, up to 25%).
If your business has W-2 employees, you owe federal payroll tax deposits monthly or semi-weekly (depending on prior-year volume) plus a quarterly Form 941 reconciliation. If you have any self-employment income or under-withholding from your W-2 job, you also owe quarterly estimated tax.
Underpayment penalty for missing quarterly estimated tax is 8% annual (compounded), applied to the shortfall for the period it was outstanding. Most years it adds up to several hundred dollars for under-savers, but high earners can owe thousands in penalty for skipped quarterly payments. See our tax strategy for $150K+ Texas earners for the broader high-income planning framework.
If you filed an extension in March or April, the extended deadlines come due in September and October.
Missing the extended deadline is materially worse than missing the original one. The failure-to-file penalty is 5% per month (up to 25% of unpaid tax) PLUS the late-payment penalty already accruing since April. A return filed even one day late after extension owes the full first-month penalty.
December is not a filing month for most small businesses, but it is the last month to make decisions that affect the current tax year.
Year-end planning is where the bulk of tax savings actually happens. Filing in April records what already occurred. Decisions made in October, November, and December change what occurs.
Form 1099-NEC is due to recipients and to the IRS by January 31 for any non-employee paid $600 or more during the prior year. Common 1099 categories include contractors, freelancers, attorneys, consultants, repair services, and rent paid to a landlord (unless landlord is a corporation).
You do NOT issue a 1099 to: (1) corporations (except attorneys, who always get one); (2) payments made via credit card or third-party network like PayPal/Stripe (those get reported on 1099-K by the processor); (3) payments for merchandise or product purchases.
Penalty for late or missing 1099: $60 per form if up to 30 days late, $130 per form if filed by August 1, $340 per form after that, $680 per form if intentional. The IRS uses 1099 mismatch as a primary audit trigger, so accurate 1099 filing protects you in two ways.
Missing a federal tax deadline triggers some combination of three penalties:
If you cannot file on time, ALWAYS file an extension. The extension is automatic and free. It costs nothing and prevents the much larger failure-to-file penalty. The extension does not extend the time to pay, so pay your estimated balance with the extension to avoid the failure-to-pay penalty.
If you have been missing deadlines and the penalty stack is real, do not just keep waiting. Get current as quickly as possible. The IRS has first-time penalty abatement available for taxpayers in good standing for prior 3 years and a few other relief programs.
The deadlines themselves are not the hard part. The hard part is the planning that happens BEFORE the deadlines: structuring payroll so payroll-tax deposits are accurate, picking the right S-Corp election timing, modeling quarterly estimates so you do not over- or under-pay, year-end equipment purchase decisions, and 1099 collection during the year so January is not a fire drill.
For most small businesses with revenue under $200K and simple structures, deadlines can be self-managed with calendar reminders and a tax preparer who files in March. Above $200K, with employees, or with an S-Corp or partnership structure, the planning value of a year-round CPA usually exceeds the cost.
If you have been doing it yourself and the deadline schedule is starting to feel like a stress test, let’s talk through a year-round structure that handles all of this in the background.
Until next time.
S-Corporations (Form 1120-S) and Partnerships (Form 1065) are due March 15 each year. Both file earlier than individual or C-Corporation returns because their owners need K-1 statements before they can file personal returns. A six-month extension is available via Form 7004, extending the filing deadline to September 15.
Quarterly estimated tax payments are due April 15 (Q1), June 15 (Q2), September 15 (Q3), and January 15 of the following year (Q4). If a date falls on a weekend or federal holiday, the deadline shifts to the next business day. Underpayment of estimates triggers an 8% annual penalty on the shortfall.
Form 1099-NEC must be issued to contractors and filed with the IRS by January 31 each year, for any non-employee paid $600 or more in the prior tax year. Late-filing penalties start at $60 per form and climb to $680 per form for intentional failures.
Missing a tax filing deadline triggers the failure-to-file penalty: 5% per month of unpaid tax, up to 25% total. Compounded by the failure-to-pay penalty (0.5% per month) if tax is owed and not paid. Always file an extension if you cannot file on time, the extension prevents the larger failure-to-file penalty and is automatic and free.
No. A filing extension (Form 4868 for individuals, Form 7004 for businesses) extends only the time to file the return. Any tax owed is still due on the original deadline. Pay the estimated balance with the extension request to avoid the failure-to-pay penalty.
Adam Traywick, CPA is the President and founding CPA of Adam Traywick, LLC, a Fort Worth small-business accounting firm. He has over 20 years of experience helping small business owners across home-services trades, hair salons, real estate, and insurance agencies optimize taxes, run cleaner books, and avoid the surprises that come from once-a-year accountants.
