Written by: Andrew Cohen, CFA, CPA, Managing Partner, Condesa Financial Group

Key Takeaways

• Startup tax compliance starts at incorporation and continues with recurring federal, state, and local filing, election, and payment obligations, even before revenue.
• Entity type (LLC, S-Corp, or C-Corp) drives which returns you file, how income is taxed, and which elections you can make.
• Deadlines such as the 30-day non-extendable 83(b) election, quarterly payroll deposits, and annual franchise tax reports carry compounding penalties that cannot be reversed.
• Stage-specific triggers like your first hire, multi-state operations, or crossing economic-nexus thresholds add new quarterly and annual obligations quickly.
• Condesa Financial helps founders map these obligations to their entity type and stage; build your compliance calendar before penalties accrue.

What Startup Tax Compliance Actually Means

Startup tax compliance is the full set of federal, state, and local filing, election, and payment obligations a startup takes on based on its entity type, payroll activity, and operating footprint. Compliance functions as a continuous calendar of obligations that begins at incorporation and expands as the company hires employees, enters new states, and crosses revenue thresholds.

Several connected concepts define the compliance landscape a founder must navigate. Entity classification determines whether the business is an LLC, S-Corp, or C-Corp, which federal return it files, whether it pays tax at the entity level or passes income through to owners, and which elections are available. That tax treatment then shapes payment obligations such as quarterly estimated taxes and payroll deposits. A fiscal or calendar year, most often a calendar year from January 1 to December 31, sets the due dates for annual returns. Quarterly estimated payments apply when expected tax exceeds IRS thresholds. Nexus rules then determine which states can require returns and payments based on physical presence, payroll, or, post-Wayfair, economic activity alone.

The decision framework that organizes every obligation in this guide rests on three questions: (1) What entity am I? (2) What stage am I at, such as pre-revenue, first hire, or multi-state? (3) Which obligations does that combination trigger? The sections below walk through each combination in sequence.

Map your compliance obligations with our team based on your entity type and stage.

Startup Tax Compliance By Entity Type: LLC vs. S-Corp vs. C-Corp

Entity type is the single most important variable in startup tax compliance. The same $200,000 in net income produces a different tax bill, a different set of required forms, and a different compliance calendar depending on whether the business is an LLC, an S-Corp, or a C-Corp.

LLC: Pass-Through Treatment, Self-Employment Tax, And The Draw Question

A default single-member LLC is treated by the IRS as a disregarded entity, and if the owner is an individual operating a trade or business, the LLC’s income and expenses are reported on Schedule C (Form 1040); rental income would instead be reported on Schedule E and farming income on Schedule F, while a default multi-member LLC is treated as a partnership and files Form 1065 with income passed through to owners on Schedule K-1. In both cases, the LLC itself pays no federal income tax. The owners pay tax on their share of the profit.

Two questions dominate LLC tax compliance for founders.

Should I Pay Myself A Salary Or Take A Draw? Under default LLC taxation, owners take an owner’s draw, which is a transfer of equity rather than a deductible wage. Owners of a default LLC (single-member disregarded entity or multi-member partnership) do not pay themselves W-2 wages and instead take owner’s draws or distributions; W-2 salary becomes available only when the LLC elects S-Corp treatment via Form 2553 or C-Corp treatment via Form 8832, after which the IRS requires the owner’s salary to reflect reasonable compensation. Because the draw is not a wage, it is not subject to payroll taxes. However, the LLC’s profit is taxable to the owner whether or not it is withdrawn.

How Much Should An LLC Put Away For Taxes? For a default LLC taxed as a sole proprietorship or partnership, a commonly recommended starting set-aside is 25%–30% of net profit for taxes, while an LLC taxed as an S corporation typically starts at 15%–20%, ideally by transferring that amount to a separate tax savings account as revenue comes in. This set-aside covers both income tax and self-employment tax. With default LLC taxation, owners generally pay self-employment tax at a 15.3% rate (12.4% Social Security plus 2.9% Medicare) on net earnings from self-employment, which are generally 92.35% of net profit. The Social Security portion is capped at the annual wage base. Under S-corporation taxation, shareholder-employees pay FICA payroll taxes only on their W-2 salary, and remaining profit distributions are not subject to self-employment or FICA tax, provided the owner first receives a reasonable salary.

S-Corp: The 2553 Election, Reasonable Compensation, And Form 1120-S

A corporation or other entity eligible to be treated as a corporation elects S-Corp status by filing IRS Form 2553 to make an election under section 1362(a). Once elected, the entity files Form 1120-S annually and issues a Schedule K-1 to each shareholder. The return is generally due by the 15th day of the 3rd month after the end of the tax year, March 15 for calendar-year S-Corps, but the deadline shifts to the next business day when that date falls on a weekend or holiday (for tax year 2025, the deadline is March 16, 2026).

The defining compliance obligation for S-Corp owners is reasonable compensation. The IRS requires S-Corp owner-employees to pay themselves a reasonable salary before taking any distributions, a standard tied to what someone in that role with comparable hours and responsibilities would earn in the open market. Paying a token salary while taking large distributions is one of the clearest audit triggers in S-Corp filings. An S-Corp election typically starts making financial sense at around $80,000–$100,000 in net business profit, saving roughly $5,000 or less below $80,000 and $8,000–$15,000+ annually above $100,000, though in California the practical break-even rises to roughly $130,000–$150,000 due to the state’s S-Corp tax and compliance costs.

C-Corp: Entity-Level Taxation, Form 1120, And The Delaware Default

Form 1120, the U.S. Corporation Income Tax Return, is used by domestic corporations to report their income, gains, losses, deductions, and credits, and to figure their income tax liability. As mentioned earlier, C-Corps pay a 21% federal corporate tax at the entity level. Shareholders then pay tax again on dividends. A C-Corp structure is warranted in three narrow scenarios: taking outside investment (VC funds and most institutional investors require C-Corp structure, typically Delaware), genuinely retaining large profits inside the entity where the 21% federal C-Corp rate beats the 32–37% personal rate, and QSBS Section 1202 planning.

For compliance purposes, the LLC-versus-C-Corp comparison is primarily about structure, not tax rates. An LLC avoids entity-level tax but subjects all profits to self-employment tax under default rules. A C-Corp pays entity-level tax but enables equity compensation structures, QSBS exclusions, and institutional investment that LLCs cannot support. An S-Corp sits between the two and combines pass-through taxation with payroll discipline. The right structure depends on the founder’s stage, investor expectations, and long-term exit plan.

Evaluate your entity structure with our experts.

Federal Filing Obligations By Entity And Stage

Once your entity type is set, the next step is understanding the federal filing obligations that apply to it. Each obligation below appears as a self-contained block with the form, the deadline, and the penalty for missing it.

Form 1120, C-Corp Annual Return

Form 1120 is due April 15 for calendar-year C-Corps, with an automatic six-month extension to October 15 available by filing Form 7004. The extension extends time to file and does not extend time to pay. For tax returns required to be filed in 2026 (due date after 12/31/2025), the IRS minimum failure-to-file penalty for a return more than 60 days late is the smaller of $525 or 100% of the tax required to be shown on the return. The failure-to-file penalty is 5% of the tax due (less any tax paid on time and available credits) for each month or partial month the return is late, up to a maximum of 25%, with interest charged separately on penalties and any unpaid balance.

Form 1120-S, S-Corp Annual Return

For calendar-year S-Corps, Form 1120-S is generally due March 15, but for the 2025 tax year the due date is March 16, 2026, because March 15 falls on a Sunday, one month before the C-Corp deadline. An extension to September 15 is available via Form 7004. Missing the Form 1120-S deadline triggers an IRS failure-to-file penalty of $255 per shareholder per month (for returns due after 12/31/2025), up to 12 months, even if the company owes no tax. A three-shareholder S-Corp that never files its Form 1120-S faces a maximum penalty of $9,180 (3 shareholders × $255 per month × 12 months) for a return due in 2026, before any tax is calculated.

Form 1065, Partnership And Multi-Member LLC Return

Form 1065 is generally due March 15 for calendar-year partnerships and multi-member LLCs classified as partnerships, but if that date falls on a Saturday, Sunday, or legal holiday, the deadline shifts to the next business day (for the 2025 tax year, the due date is March 16, 2026), with an extension to September 15 via Form 7004. The penalty structure mirrors Form 1120-S. For returns required to be filed in 2026, the penalty is $255 per partner per month (or partial month), up to 12 months, under IRC §6698 as adjusted by Rev. Proc. 2024-40.

Stage Differences Matter

A pre-revenue Delaware C-Corp with no employees must file federal Form 1120, pay Delaware franchise tax plus the $50 annual report fee by March 1, and file Form 5472 with its 1120 if it is at least 25% foreign-owned and had a reportable transaction with a related party. A 40-person Series A company with multi-state payroll must file Form 941 quarterly for federal employment taxes, Form 940 annually for federal unemployment, issue W-2s and W-3 and 1099-NECs at year-end, and register for state income tax withholding and SUTA in every state where it has employees. The same company may also need sales tax registrations in states where economic nexus thresholds, typically $100,000 in sales or 200 transactions, have been crossed, though sales tax nexus is distinct from payroll tax nexus. IRS Publication 583 and the IRS Business Tax Account are the primary federal references for founders mapping their obligations at each stage.

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Payroll, Contractor, And Worker Classification Compliance

The moment a startup hires its first W-2 employee, a new layer of compliance obligations begins. These obligations are quarterly and annual, and the penalties for late deposits are not dischargeable.

Form 941, Quarterly Payroll Tax Return

Form 941 is the Employer’s Quarterly Federal Tax Return, filed by employers who withhold income, Social Security, or Medicare tax from employee paychecks or who owe the employer’s portion of Social Security or Medicare tax. Form 941 is generally due by the last day of the month following the end of the quarter, April 30, July 31, October 31, and January 31, though employers who made timely deposits in full payment may file by the 10th day of the second month after the quarter ends, and deadlines falling on a weekend or legal holiday move to the next business day. Under IRC § 6656, late payroll tax deposits trigger a tiered Failure to Deposit Penalty of 2% of the unpaid deposit for deposits 1–5 days late, 5% for 6–15 days late, 10% for more than 15 days late, and 15% for amounts still unpaid more than 10 days after the first IRS notice or the day notice and demand for immediate payment is given; the tiers replace rather than stack.

Form 940, Annual Federal Unemployment Tax

Form 940 is the Employer’s Annual Federal Unemployment (FUTA) Tax Return, generally due January 31 of the following year (for tax year 2025, due February 2, 2026, or February 10, 2026 if all FUTA tax was deposited when due). Multi-state employers file Schedule A (Form 940) for credit reduction information.

W-2, W-3, And 1099-NEC

Employers furnish Form W-2 to employees and file Copy A of Form W-2 with the Social Security Administration, accompanied by Form W-3, except when e-filing, in which case no separate Form W-3 filing is required because the SSA’s online service creates an electronic Form W-3 automatically. For tax year 2025 payments, startups must issue W-2s to employees and 1099-NECs to contractors paid $600 or more by January 31; for payments made in 2026, the 1099-NEC threshold rises to $2,000 and the deadline shifts to February 2, 2026 because January 31 falls on a Saturday. For information returns due in 2026, the IRS penalty for failing to file a required 1099-NEC is $60 per form if filed within 30 days of the deadline, $130 if filed after 30 days but by August 1, and $340 if filed after August 1 or not filed at all; a startup with 20 contractors that misses the January 31 deadline and files after August 1 (or not at all) could face up to $6,800 in penalties under the 2026 IRS penalty schedule ($340 per form × 20); the $6,200 figure corresponds to the lower 2024 tax-year rate of $310 per form.

Worker Classification: 1099 vs. W-2

Worker classification is a compliance decision with real financial consequences. Misclassifying an employee as a contractor exposes a startup to back payroll taxes, penalties, and interest, with the IRS generally able to assess back employment taxes for open years, typically three years, or longer for fraud, and applies a multi-factor worker classification test. Form SS-8 is used to request an IRS determination of worker status for purposes of federal employment taxes and income tax withholding, the form a startup files when contractor-versus-employee classification is in dispute. The IRS does not accept the label a contract uses. It evaluates the actual working relationship. Beyond federal payroll rules, startups must also navigate a patchwork of state and local obligations.

State And Local Obligations: Franchise Tax, Nexus, And Remote Workers

Delaware Franchise Tax

Delaware domestic C-Corps owe annual franchise tax due March 1, calculated using either the Authorized Shares Method (minimum $175) or the Assumed Par Value Capital Method (minimum $400), whichever results in the lesser tax, with a maximum of $200,000. The default Authorized Shares Method can produce a bill of $50,000+ for startups with large authorized share counts, while for early-stage companies the Delaware Assumed Par Value Capital Method typically reduces the franchise tax to the $400 statutory minimum, which with the $50 annual report fee amounts to about $450, well under $500. The annual report and the franchise tax are separate obligations filed together. Most early-stage startups should calculate both methods and pay the lower amount.

Post-Wayfair Economic Nexus For SaaS And Digital Goods

The single most common compliance surprise for 2024–2026 startups is discovering they owe sales tax in states where they have never had a physical presence. Following the Supreme Court’s 2018 South Dakota v. Wayfair decision, US states can require out-of-state sellers to collect and remit sales tax once they cross economic nexus thresholds in that state, most commonly $100,000 in annual sales or 200 transactions, though thresholds range from $10,000 to $500,000 and many states have repealed the transaction test.

For SaaS and digital goods companies, the analysis is two-part. First, the startup must determine whether it has economic nexus in a given state. Second, it must determine whether the product is taxable in that state. These are independent questions. As of 2026, states tax SaaS through three distinct legal routes: as tangible personal property (Hawaii, New Mexico, South Dakota, Washington), as a taxable service (Texas, Tennessee, Ohio, Connecticut, D.C.), or as a nontaxable intangible service (California, Florida, Illinois, Nevada, North Carolina, Oklahoma, Virginia), though the “nontaxable” classification in several of these states is time-limited and subject to pending legislative changes such as California’s scheduled 2027 taxation of SaaS.

A single $120,000 enterprise contract can establish economic nexus for a SaaS company in a state even with no other customers there, but only in states whose economic nexus threshold is $100,000 in gross sales, the same thresholds mentioned earlier; states with higher thresholds such as California, New York, and Texas ($500,000) would not be triggered by that amount. Sales tax audit exposure typically includes penalties of 5% to 25% of the unpaid tax for negligence or late filing (with fraud penalties reaching 50% to 75% in many states), plus interest that accrues from the original due date and can add 25% or more over a four-year audit period. A Voluntary Disclosure Agreement can limit the look-back period and waive penalties when the startup acts before the state makes contact.

Remote Workers And Multi-State Nexus

Startups with remote employees in multiple states may have state income tax or franchise tax filing obligations in each state where they have nexus, a physical or economic presence, not just their state of incorporation. A distributed team of five engineers in five different states can create five separate state payroll tax registrations, five state income tax filing obligations, and five sets of annual reports. This outcome is the default result of remote hiring without a compliance review.

The 83(b) Election: A 30-Day, Non-Extendable Deadline

Under IRC §83(b)(2), a Section 83(b) election must be filed not later than 30 days after the date of the property transfer (the grant or early-exercise date). The 30-day window is statutory and non-extendable, with no discretionary IRS authority to waive it and no reasonable-cause or hardship exception; courts have enforced the deadline against taxpayers whose lawyers made the mistake or who were seriously ill, and the only softening rules are mechanical (weekend/holiday rollover under IRC §7503 and disaster or combat-zone postponements under IRC §7508A).

The election applies to restricted stock awards (RSAs) and early-exercised stock options. RSUs and unexercised stock options are not eligible for an 83(b) election because there is no property transfer yet; RSUs are a promise of future shares and an unexercised option is a right, not stock.

Without the election, restricted stock is taxed by default as ordinary income each year as shares vest, based on the fair market value on each vesting date minus any amount paid for the shares, reported as W-2 wages and taxed at the recipient’s marginal rate (up to 37% federal plus state) along with payroll taxes. With a timely election filed when the stock is worth near zero at formation, the taxable income at grant is effectively zero. For a founder receiving 1,000,000 restricted shares at $0.0001 per share ($100 total) on a four-year vest, filing an §83(b) election results in $0 of federal tax at grant because the fair market value equals the price paid, versus roughly $5,000,000 of ordinary income taxed at up to 37% (approximately $1.85 million) over the vesting period if the election is not filed.

As of 2026, the IRS publishes Form 15620, Section 83(b) Election (revised April 2025), as the standardized filing format for making an IRC § 83(b) election, though taxpayers may alternatively file a written statement satisfying Treas. Reg. § 1.83-2. Since late July 2025, Section 83(b) elections can be completed and submitted online through an IRS online account using ID.me authentication and Form 15620, though a written election containing the required information may still be filed on paper. A copy must also be provided to the employer. Under the §7502 mailbox rule, a Section 83(b) election sent by certified mail is treated as filed on its postmark date even if the IRS receives it later, but because recent USPS operational changes mean a mailpiece may receive a postmark date later than the date it was deposited, taxpayers should not assume that dropping the election in the mail on day 30 guarantees a timely postmark.

The R&D Tax Credit: Form 6765 And The Payroll-Tax Offset

The Inflation Reduction Act of 2022 increased the maximum payroll tax research credit a qualified small business can elect from $250,000 to $500,000 for tax years beginning after December 31, 2022. This increase creates a significant opportunity: up to $500,000 per year of federal R&D credit applied against the employer portion of payroll taxes, Social Security first, then Medicare, rather than against income tax liability. For a pre-profit startup with no income tax to offset, this structure converts the credit into immediate cash flow.

To qualify as a Qualified Small Business (QSB) for the payroll-tax offset, a company must have gross receipts of less than $5 million in the credit year and no gross receipts in any tax year before the five-year window ending in the credit year.

The election for the R&D payroll-tax offset is made by a qualified small business completing Section D of Form 6765, Credit for Increasing Research Activities, and filing it with the company’s timely filed income tax return, including extensions. The election cannot be made on an amended return, and taxpayers other than partnerships and S corporations must complete Form 3800 before completing Section D. The election cannot be made with an amended return. The credit is then applied on Form 8974, Qualified Small Business Payroll Tax Credit for Increasing Research Activities, which must be completed and attached to the company’s employment tax return.

Startup Tax Compliance Checklist And Filing Calendar

This checklist and calendar summarize the core obligations for a calendar-year startup, with each step tied to a form and deadline in chronological order.

1. Obtain an Employer Identification Number by filing Form SS-4 before filing any business return or payroll form, required at incorporation.
2. File the 83(b) election on Form 15620 within 30 calendar days of the restricted stock transfer date; this deadline is non-extendable.
3. Make quarterly estimated tax payments on April 15, June 15, September 15, and December 15 for C-Corps, or April 15, June 15, September 15, and January 15 for individuals and pass-through owners, using Form 1040-ES or EFTPS.
4. File quarterly payroll returns on Form 941 by April 30, July 31, October 31, and January 31 for any startup with W-2 employees.
5. Issue W-2s to employees and 1099-NECs to contractors by January 31 for 2025 payments, or by February 2, 2026 for 2026 payments, and file W-3 with the Social Security Administration when required.
6. File the annual federal unemployment return on Form 940 by January 31 of the following year, with the slight calendar shifts noted in IRS instructions.
7. File the annual corporate or partnership return, using Form 1120 for C-Corps due April 15, Form 1120-S for S-Corps due March 15 or the next business day, or Form 1065 for multi-member LLCs due March 15 or the next business day.
8. Elect the R&D payroll-tax offset by completing Section D of Form 6765 on the timely filed income tax return for any QSB with qualifying research expenses.
9. File the Delaware franchise tax report and pay by March 1 using the Assumed Par Value Capital Method when that method minimizes the bill for early-stage companies.
10. Register for sales tax in any state where economic nexus thresholds have been crossed, and file returns in those states on the required schedule.