Quick overview

Starting a business triggers a set of federal and state filing deadlines that vary by entity type, payroll activity, and the taxes you collect. Missed deadlines can trigger penalties, interest, and increased compliance risk. This checklist translates those obligations into practical dates and actions you can use during your company’s first 12 months.

This guidance is educational and current as of 2025. For personalized tax planning, consult a CPA or tax attorney. See IRS publications for official rules (for example IRS Publication 583 and the IRS small business filing guidance).

Sources: IRS Publication 583 (Starting a Business) and the IRS business filing pages (see links below).

Filing calendar basics (what to expect)

  • Estimated tax payments: typically due quarterly (April, June, September, and January of the following year) for owners who expect to owe federal income tax beyond what is withheld. See IRS Form 1040-ES guidance for individuals and Schedule C filers.
  • Income tax returns: due dates depend on entity type — sole proprietors (Schedule C on Form 1040) generally follow the individual deadline; partnerships and S corporations usually file earlier (March 15 for calendar-year filers); C corporations typically file by April 15 for calendar-year filers.
  • Payroll deposits and returns: employers deposit payroll taxes according to deposit schedules (semiweekly or monthly) and file Form 941 quarterly (due the last day of the month after each quarter). Annual payroll returns include Form 940 for FUTA and W-2/Forms W-3 to SSA (generally due end of January). See IRS Form 941 and Form 940 instructions for details.
  • Information returns: Form 1099-NEC (nonemployee compensation) and Form 1099-MISC (other payments) have specific delivery and filing dates—pay attention to the January 31 deadline for payer reporting of nonemployee compensation in Box 1 (1099-NEC). Also check state 1099 filing rules.
  • State and local filings: sales tax, state income/franchise tax returns, and annual registration or annual reports have separate deadlines and can be different from federal dates — register with your state’s tax agency immediately after formation.

Note: the exact dates can change if the statutory date falls on a weekend or holiday. Always confirm current-year dates via the IRS website or your state tax agency.

First‑year checklist by timing

Day 0–30 (right after formation)

  • Get an EIN from the IRS if you plan to hire employees, have partners, incorporate, or prefer not to use your SSN. (IRS: apply online for an Employer Identification Number.)
  • Register for state employer withholding and sales tax accounts if you will have employees or will collect sales tax.
  • Decide on accounting method (cash vs. accrual) and your tax year (calendar vs. fiscal). These choices affect filing forms and deadlines.
  • Open a dedicated business bank account and set up bookkeeping software to track income, expenses, and payroll.

Month 1–3

  • If you expect to owe tax, estimate quarterly payments and submit the first payment if it’s near or after your start month. Independent contractors and single‑member LLC owners commonly need to make estimated payments. (See our internal guide about estimated taxes: “Estimated Tax Payments: Who Pays, When, and How to Calculate” and “Estimated Tax Payments for Independent Contractors”.)
  • If you hired employees, set up payroll deposits (electronic Federal Tax Payment System — EFTPS) and establish your deposit schedule with the IRS.
  • If your entity is a partnership or S corp, calendar your March 15 return deadline (Form 1065 or Form 1120‑S) and gather partner/shareholder K-1 and basis information.

Quarterly rhythm (typical federal schedule for calendar‑year taxpayers)

  • April 15 (or the taxpayer deadline for the year): personal returns/sole proprietors (Schedule C on Form 1040), second quarter estimated payment due (note: if you started in January, your first estimated payment may be due in April). C corporations — Form 1120 due.
  • June 15: third quarter estimated tax due for individuals and many pass‑through owners.
  • September 15: fourth quarter estimated tax due for individuals and pass‑through owners.
  • January 15 (following year): final estimated payment for the prior tax year (or safe harbor/application of the annualized method).
  • Employer returns (Form 941) are due quarterly — typically by April 30, July 31, October 31, and January 31 for the preceding quarter’s payroll. FUTA (Form 940) and Forms W‑2/W‑3 have end‑of‑January deadlines for filing and furnishing to employees.

For a practical reference, the site guide “Quarterly Estimated Tax Calendar and Calculation Guide” is a useful step‑by‑step resource.

Checklist by entity type (practical tasks and deadlines)

Sole proprietorship (Schedule C, single‑member LLC taxed as sole proprietor)

  • File Schedule C on Form 1040 by the individual tax deadline (generally April for calendar‑year filers). File Form 1040 extension (Form 4868) if you need more time to file — remember an extension to file is not an extension to pay.
  • Make quarterly estimated payments using Form 1040‑ES if you expect to owe $1,000 or more in tax after withholding.
  • Keep records for self‑employment tax (Social Security/Medicare) and plan for the Schedule SE calculation.

Partnerships (Form 1065) and S corporations (Form 1120‑S)

  • File the entity return by March 15 for calendar‑year filers; provide K‑1s to partners/shareholders so they can include income on their individual returns.
  • The partnership/S‑corp may need to make estimated tax payments on behalf of owners for certain circumstances (e.g., built‑in gains tax for S corps, or composite returns depending on state rules).

C corporations (Form 1120)

  • File Form 1120 by April 15 for calendar‑year filers, unless you elect a fiscal year.
  • Corporations may have different estimated tax rules (generally pay estimated corporate income taxes) — speak to your tax advisor about corporate estimated tax calculations.

Employers

  • Deposit payroll taxes according to your EFTPS deposit schedule (monthly, semiweekly, depending on payroll amounts).
  • File Form 941 quarterly and Form 940 annually (or as required). Provide W‑2s/W‑3 to employees and the SSA by the required January deadline.

Retail / sales tax collectors

  • Register for your state sales tax permit immediately. Sales tax filing frequency depends on volume (monthly, quarterly, annual) and states vary on thresholds.

Common first‑year pitfalls (and how to avoid them)

  • Confusing filing vs. payment deadlines: an extension to file (Form 4868 or Form 7004) does not extend the payment deadline. Always estimate and pay what you expect to owe by the original due date to avoid penalties and interest.
  • Underestimating estimated taxes: use safe‑harbor rules to avoid underpayment penalties — generally pay 100% of prior year tax (110% for higher incomes) or 90% of current year tax; annualized methods apply for businesses that ramp up sales midyear. See IRS estimated tax rules.
  • Missing payroll deposit schedules: payroll deposit rules can be strict and penalties for late deposits are often higher than for late returns. Automate EFTPS deposits and reconcile payroll weekly or monthly.
  • Ignoring state and local deadlines: sales tax returns, state income/franchise taxes, and annual business reports are separate obligations. Mark state filing dates immediately after formation.

Tools and practical tips I use with clients

  • Build a master tax calendar in your accounting system or calendar app with notifications 30, 14, and 2 days before each deadline.
  • Reconcile income monthly and run a simple projected income statement to estimate quarterly payments.
  • Use accounting software that automates 1099 tracking, payroll tax calculations and deposit reminders.
  • When revenue is seasonal, consider the annualized estimated tax method to reduce underpayment penalties.
  • If you miss a deposit or payment, correct it immediately and document steps to prevent reoccurrence. If penalties occur, many first‑time or reasonable‑cause penalty abatement options exist — consult a tax professional.

In my practice working with hundreds of new business owners, the clients who succeed most often set up bookkeeping, payroll, and a tax calendar in the first month and review estimated tax projections at least quarterly.

How to handle missed deadlines

  1. File the required return as soon as possible — filing reduces penalties compared with not filing at all.
  2. Pay as much of the tax owed as you can; interest accrues from the original due date.
  3. If you have a reasonable cause (serious illness, natural disaster, incorrect professional advice), you can request penalty relief — document the facts and include a statement with your return or use the IRS penalty relief procedures.
  4. For payroll deposit and trust fund recovery penalties, consult a CPA or tax attorney quickly; these penalties can be assessed against responsible individuals.

Where to find official guidance

Also see related FinHelp articles:

Final notes and disclaimer

This checklist is intended as an educational resource, not tax advice. Tax law changes and state rules can modify deadlines and requirements. For tailored guidance, consult a qualified CPA or tax attorney familiar with your industry and state. I share the practices I use with clients to reduce surprises in year one: set up systems early, monitor cash flow monthly, and schedule quarterly tax check‑ins with your advisor.

Last reviewed: 2025. Official IRS pages linked above are the authoritative source for filing dates and procedures.