US Federal Income Tax Preparation for Businesses
US businesses file federal income tax on the form that matches their entity: Form 1120 for C corporations, 1120-S for S corporations, 1065 for partnerships or Schedule C with Form 1040 for sole proprietors. Calendar-year S corporation and partnership returns are due 15 March, and C corporation returns 15 April.
Implemented by ERPHUBs · United StatesClean books are the foundation of a correct federal return
The United States taxes business income at the federal level and again in most states. The form you file depends on how the entity is classified for tax, not on the state you incorporate in.
We keep your Zoho Books chart of accounts aligned with tax line items, reconcile bank and card accounts, and hand your CPA a complete, tie-out-ready package. Return signing and advice stay with a licensed preparer.
Key rules at a glance
- C corporation: Form 1120, flat 21% federal rate, due the 15th day of the 4th month after year end.
- S corporation / partnership: Forms 1120-S and 1065 pass income to owners; due the 15th day of the 3rd month.
- Sole proprietor / single-member LLC: Schedule C filed with Form 1040.
- Extensions: Form 7004 gives six extra months to file, not to pay.
- Estimated tax: Quarterly payments, generally 15 Apr, 15 Jun, 15 Sep and 15 Jan.
- Federal VAT: None. The US has no federal value-added tax.
Federal Income Tax Filing: scope of service
Entity-aligned books
Chart of accounts mapped to the right return lines.
Reconciliations
Bank, card and loan reconciliations before year end.
Estimated tax
Quarterly projections from year-to-date profit.
Depreciation
Fixed-asset registers for Section 179 and bonus depreciation workings.
Owner activity
Distributions, basis and reasonable-compensation records for S corporations.
CPA hand-off
Trial balance, schedules and source documents delivered to your preparer.
United States compliance calendar
Dates shown are the general statutory dates; they move with your year-end, entity type and any extension.
31 January
W-2 and 1099-NEC deadlines.
15 March
Forms 1120-S and 1065 (calendar year).
15 April
Form 1120 and Schedule C filers; Q1 estimated tax.
15 June
Q2 estimated tax.
15 September
Q3 estimated tax; extended 1120-S and 1065 due.
15 October
Extended Form 1120 and 1040 due.
Set-up in Zoho Books
- Confirm the entity's federal tax classification and fiscal year.
- Align Zoho Books accounts to return categories.
- Separate personal and business transactions and clear owner draws.
- Record fixed assets and loans with supporting documents.
- Close the year with a locked period and an accountant's review.
What we watch for
- Missing the 15 March S corporation or partnership date, which carries per-owner penalties.
- Mixing owner and business expenses.
- Underpaying estimated tax and incurring penalties.
- Treating contractors as employees or the reverse.
Federal Income Tax Filing: common questions
It depends on tax classification: C corporations file Form 1120, S corporations 1120-S, partnerships and multi-member LLCs 1065, and sole proprietors report on Schedule C with Form 1040.
No. Form 7004 extends the filing deadline only; estimated tax owed is still due on the original date.
No. Sales tax is levied by states and localities. See our state sales tax filing page.
No. We prepare the books and workpapers; a licensed CPA or enrolled agent signs and files.
General guidance for United States, last reviewed 2026-10-16; it is not tax advice. Rates, thresholds and dates change, so confirm with a qualified local adviser. Official sources: IRS
A practical guide for United States businesses
From books to return: how the numbers flow
A federal return is a re-presentation of your books. Revenue, cost of goods sold and deductible expenses come from the ledger, adjusted for items the tax code treats differently, such as meals, penalties, depreciation and certain accruals. We prepare a book-to-tax schedule so every adjustment is visible and can be explained to a reviewer or the IRS.
Entity type drives everything. A C corporation pays tax at the entity level. An S corporation or partnership passes income through to owners on Schedule K-1, who pay on it whether or not cash was distributed. A single-member LLC or sole proprietor reports on Schedule C. Choosing and documenting the right classification is the first step, and elections such as S status carry their own deadlines.
Depreciation, equipment and the choices that change your bill
Equipment, vehicles, software and improvements are capitalised and recovered through depreciation rather than expensed at once. The tax code offers accelerated options, including Section 179 expensing and bonus depreciation, whose limits and percentages have changed in recent years. We keep a fixed asset register in Zoho Books with in-service dates, cost and class so the choice can be made once, with the numbers in front of you, instead of at the filing deadline.
Other recurring areas where clean records change the outcome include home office and vehicle deductions, the treatment of owner health insurance, research credits for qualifying development work, and the deduction available to certain pass-through owners. Whether each applies is a decision for your CPA; our job is to have the evidence ready.
Estimated tax and avoiding penalties
US tax is pay-as-you-go. Corporations and individual owners generally make quarterly estimated payments, and underpaying triggers an interest-like penalty even if the full balance is paid with the return. Safe harbours based on prior-year tax or current-year tax can remove the penalty, so we model both and recommend the lower, safer payment.
If you cannot file by the due date, Form 7004 for business returns and Form 4868 for individuals extend the time to file, not the time to pay. We estimate the balance due before the original deadline so the extension does not become a penalty.
- Keep a separate business bank account and card
- Record owner distributions and loans on a schedule, not as expenses
- Reconcile payroll to Forms 941 before year-end
- Collect Forms W-9 from contractors and file 1099-NEC by 31 January
Which federal return does each entity file?
| Entity | Main return | Owner reporting |
|---|---|---|
| C corporation | Form 1120 | Dividends reported by shareholders |
| S corporation | Form 1120-S | Schedule K-1 to shareholders |
| Partnership or multi-member LLC | Form 1065 | Schedule K-1 to partners |
| Sole proprietor or single-member LLC | Schedule C with Form 1040 | Reported directly on Form 1040 |
More questions about this topic in United States
We prepare books and supporting schedules and work alongside your CPA or enrolled agent, who signs and files. Where you want a signed return, we coordinate it with a licensed preparer.
It can reduce self-employment tax for profitable owner-operators but adds payroll and compliance duties. It is a tax planning decision for your CPA; clean books give them the numbers to decide.
An extension gives more time to file the return. Tax is still due on the original date, and interest and penalties run on unpaid amounts.
Yes. We rebuild and reconcile prior-year books so late or amended returns can be prepared on reliable numbers.
This guide is general information based on published United States rules and is not legal or tax advice. Rates, thresholds and due dates change; confirm current figures with the tax authority or your adviser.
Get Federal Income Tax Filing right the first time
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