Business Tax Returns

Your business entity type directly determines which tax form you file and how much tax you owe. The IRS recognizes three primary entity types: S-Corps (Form 1120-S), partnerships (Form 1065), and C-Corps (Form 1120). Each has unique filing requirements, deadlines, and tax treatment.

S-Corps (Form 1120-S) are pass-through entities commonly chosen by service businesses, consultants, and small manufacturers. The S-Corp itself files Form 1120-S, but pays no federal income tax. Instead, business income flows through to owner K-1 schedules. Owners then report K-1 income on their personal Form 1040. The critical advantage: S-Corps pay self-employment tax only on W-2 wages paid to the owner, not on distributions.

Partnerships (Form 1065) are the default structure for multi-member LLCs and joint business ventures. Form 1065 is an informational return—the partnership pays no tax. Each partner receives a Schedule K-1 showing their proportional share of income, deductions, and credits. Partners self-report the K-1 information on their personal returns. Partnerships are attractive for real estate partnerships and professional joint ventures.

C-Corps (Form 1120) are separate legal entities taxed at corporate rates. C-Corps file Form 1120 and pay federal income tax directly. Shareholders then pay personal income tax on dividends received, creating "double taxation." However, C-Corps are ideal for businesses that reinvest profits or plan to go public.

Form 1120-S is the most popular business tax return for owners earning $80,000 to $500,000 annually. The S-Corp structure allows owners to split business income into two categories: W-2 wages (which are subject to SE tax) and distributions (which are not subject to SE tax). This split creates significant tax savings.

To file Form 1120-S, you must first elect S-Corp status using Form 2553 (Election by a Small Business Corporation). Form 2553 must be filed by March 15 of the tax year you want the election effective, or within 75 days of starting your business. The IRS accepts late elections only if you meet specific "reasonable cause" criteria.

Form 1120-S requires reporting:

• All business income and expenses (Schedule C-equivalent)
• Depreciation schedule (Form 4562)
• Owner W-2 wages and amounts withheld
• Distributions paid to each shareholder
• Schedule K showing pass-through items
• Schedule K-1 for each shareholder

Filing deadline for Form 1120-S is March 15. File Form 4868 by March 15 to extend until September 15 (note: payment is still due March 15). We file most S-Corp returns on extension in September to allow time for accurate K-1 preparation.

Form 1065 (Partnership Return of Income) is required for any business with two or more owners that is not a C-Corp. This includes general partnerships, limited partnerships, multi-member LLCs, and joint ventures. Form 1065 is an informational return only—the partnership itself pays zero federal income tax. Instead, income and losses pass through to partners via Schedule K-1.

Each partner receives a Schedule K-1 showing their:

• Share of ordinary business income or loss
• W-2 guaranteed payments (if applicable)
• Capital gains/losses
• Section 179 deductions
• Depreciation recapture
• Qualified business income (QBI) for 20% deduction

Form 1065 also requires Schedule M-1 (reconciliation) showing how book income differs from tax income. This schedule is heavily scrutinized in audits, particularly if there are timing differences or permanent book/tax differences.

Real estate partnerships and real estate investment trusts (REITs) file Form 1065 with additional complexity: cost segregation studies, component depreciation schedules, and passive activity loss limitations. We specialize in real estate partnership filings and coordinate depreciation across multiple properties.

Form 1120 (Corporate Income Tax Return) is filed by C-Corporations, which are taxed as separate entities. The C-Corp calculates its own taxable income, pays federal income tax at the corporate rate, and then shareholders pay personal income tax on dividends. This "double taxation" sounds negative, but C-Corps are optimal for high-profit businesses that retain earnings or plan venture funding.

The current federal C-Corp tax rate is a flat 21% (since the 2017 Tax Cuts and Jobs Act). However, state-level corporate taxes add 3-12% depending on your state, resulting in combined effective rates of 24-33%.

Form 1120 filing requirements include:

• All income and expense reporting (similar to business returns)
• Depreciation schedule (Form 4562) with asset-level detail
• Schedule M-1 reconciling book to tax income
• Estimated tax payment tracking
• Dividend paid to shareholders information
• Officer compensation and reasonableness analysis

C-Corporations have March 15 filing deadline (or October 15 with extension). Reasonable compensation for officer-employees is critical: the IRS challenges "excessive" salaries and inadequate dividends, attempting to reclassify salary as hidden dividends to disallow deductions.

Tax deadlines vary by entity type. S-Corps and partnerships file Form 1120-S and Form 1065 by March 15. C-Corporations file Form 1120 by March 15 (for calendar-year corporations) or April 15 (for fiscal-year corporations). Sole proprietors file Form 1040 with Schedule C by April 15.

Extensions: File Form 4868 (for individuals) or Form 7004 (for businesses) by the original deadline to extend filing by 6 months. Extensions extend filing only—they do not extend payment deadlines. Estimated taxes must be paid by the original deadline or penalties apply.

State Filings: Most states require business returns by the same dates as federal returns. Some states have earlier deadlines (Illinois partnerships due March 1). We file federal and state returns simultaneously to ensure compliance across all jurisdictions.

Businesses that expect to owe $1,000 or more in federal tax (beyond W-2 withholding) must make quarterly estimated tax payments. For S-Corps, partnerships, and C-Corps, estimated payments are due April 15, June 15, September 15, and January 15.

The quarterly payment amount is based on either (1) 90% of current year tax, or (2) 100% of prior year tax (110% if prior year AGI exceeded $150,000). Most taxpayers use the prior-year safe harbor method because it's predictable and avoids surprise underpayment penalties.

We calculate quarterly estimates for all clients with business income. For S-Corps, we calculate based on W-2 wages withheld plus expected distributions. For partnerships, we estimate based on projected K-1 income. For C-Corps, we estimate the corporate tax liability.

We send quarterly payment reminders and estimates to all business clients. We also provide IRS payment vouchers (Form 1040-ES for individuals, Form 1120-W for corporations) with payment instructions.

The IRS selects certain business returns for examination based on patterns that historically correlate with underreporting. Understanding these triggers helps you avoid them when possible and prepare defensively when they apply to your situation.

Common Audit Triggers:

• Disproportionate deductions: Business expenses that exceed industry norms. The IRS compares your expense ratios to industry standards published by the IRS.
• Home office deduction: Claiming 100% of your home as office space, or deductions that seem inflated for home office use.
• Large casualty losses: Claiming theft or disaster losses without proper documentation.
• Related-party transactions: Payments to spouses, children, or other related entities without clear business purpose or documentation.
• Hobby loss deduction: Net losses claimed in consecutive years without apparent profit motive (Form 8949).
• Inconsistent Schedule C/K-1 reporting: Reporting different income amounts on your personal return vs. business return.
• Large charitable donations: Donations that seem excessive relative to income, particularly non-cash donations.
• Unreasonable officer salary: C-Corps paying excessive salaries or inadequate dividends (IRS expects salary + dividend, not just salary).

To file your business return efficiently and accurately, gather these items before your meeting with your CPA. Providing complete documentation upfront prevents delays and reduces the likelihood of amended returns.

Once you file with Taxstra, we become your ongoing tax partner. We provide:

• Monthly or quarterly profit & loss reviews
• Estimated tax payment calculations
• Year-round tax planning and strategy
• Estimated quarterly reminders and payment vouchers
• Year-end tax optimization