US Tax Preparation Services

US tax preparation for individuals, LLCs and corporations

US tax rules differ by entity type, state and the owner's residency. We prepare federal and state returns for individuals, single-member and multi-member LLCs, S-corporations and C-corporations, and plan during the year so there are fewer surprises at filing time. Every return is reviewed by a second accountant before it is filed.

Returns we prepare

• Form 1040 and 1040-NR for US residents, citizens abroad and non-resident individuals
• Form 1065 for partnerships and multi-member LLCs
• Form 1120-S for S-corporations
• Form 1120 for C-corporations, including pro forma returns for foreign-owned LLCs
• State income, franchise and annual report filings
• Quarterly estimated tax calculations and extensions

Tax planning through the year

Filing is only the last step. We review your entity structure, estimated payments, deductible expenses and timing of income so that you can decide before year end, not after. Whether an LLC, S-corp or C-corp suits you is one of the most valuable questions to answer early; see our guide to choosing between them.

Tax help for foreign-owned and cross-border businesses

If you own a US company from outside the US, you may owe no US income tax and still have required filings. We assess whether your income is US-connected, prepare the right returns and make sure information forms are filed on time. See whether non-residents pay US tax on LLC income.

Important dates

Key dates include January 31 for W-2 and 1099-NEC forms, March 15 for partnership and S-corporation returns, and April 15 for individual and C-corporation returns, with extensions available. Full details are in our tax deadlines guide.

How US tax preparation works for businesses

US tax preparation is the process of turning a year of financial records into accurate federal and state returns. It starts with the books, because a return can only be as reliable as the numbers behind it. Income is totalled, expenses are classified as deductible or not, owner activity such as contributions and distributions is separated from business activity, and the result is reported on the form that matches the legal structure of the business.

The structure decides almost everything. A sole proprietor or single-member LLC reports business profit on Schedule C of the owner's Form 1040. A multi-member LLC taxed as a partnership files Form 1065 and issues a Schedule K-1 to each member. An S-corporation files Form 1120-S, and a C-corporation files Form 1120 and pays its own federal income tax. If you are unsure which applies to you, our guide to LLC vs S-corp vs C-corp explains the differences.

Beyond the federal return, most businesses also face state and local obligations. These can include state income or franchise tax, annual report fees, sales and use tax, payroll tax accounts and city or county business licences. We prepare the returns that apply to your entity and the states where it operates, and we flag registrations you may have missed.

Returns and forms we prepare

Our tax preparation service covers the returns most small businesses, startups and international founders need each year:

• Form 1040 with Schedule C for sole proprietors and single-member LLCs owned by US taxpayers.
• Form 1040-NR for non-resident individuals who have US-source or effectively connected income.
• Form 1065 and Schedule K-1 for partnerships and multi-member LLCs.
• Form 1120-S for S-corporations, including reasonable-compensation review for owner-employees.
• Form 1120 for C-corporations, including startups that plan to raise venture capital.
• Form 5472 with a pro forma 1120 for foreign-owned US LLCs and corporations.
• State returns, annual reports and franchise tax filings in the states where you are registered.
• Sales tax returns and nexus reviews for sellers who ship or deliver across state lines.

Each return is prepared from your reconciled books, checked against the prior year for unexplained changes and reviewed by a second accountant before we ask you to sign. Returns are filed electronically wherever the IRS or the state allows it, and you receive a copy of everything we submit.

Key federal deadlines to plan around

For businesses that use a calendar tax year, the main federal return deadlines are March 15 for partnerships and S-corporations, and April 15 for C-corporations and individuals. Weekends and federal holidays can move a date, and fiscal-year entities have different dates. A business can request an automatic extension of time to file, generally six months, with Form 7004, and individuals can use Form 4868. An extension gives you more time to file but does not give you more time to pay, so any tax you expect to owe should still be estimated and paid by the original due date.

Estimated tax payments follow their own calendar, normally in April, June, September and January. Self-employed owners and many pass-through owners make them with Form 1040-ES, and corporations make them with their own estimated-tax process. Our guide to quarterly estimated taxes explains safe harbor rules, and our US tax deadlines page lists the dates in one place.

Missing a date has a cost. The IRS can charge a failure-to-file penalty of 5% of the unpaid tax for each month, up to 25%, plus a failure-to-pay penalty and interest. Information returns carry separate penalties, and some are much larger than the tax itself, which is why we keep a filing calendar for every client.

Tax planning: what we look at during the year

Preparation looks backward. Planning looks forward, and the best time to reduce a tax bill is before the year ends. We review your year-to-date profit with you at set points and discuss the choices that are still open.

• Entity and election review: whether your current structure still fits your profit level, owner residency and growth plans.
• Owner pay: how salary, distributions and guaranteed payments are set, and how self-employment tax applies, which is 15.3% on net earnings up to the Social Security wage base and 2.9% Medicare above it.
• Deductions and credits: business expenses, retirement contributions, home-office use where it qualifies, equipment purchases and the qualified business income deduction where an owner is eligible.
• Timing: when income is recognised and when large expenses are paid or invoiced.
• Estimated payments: sizing quarterly payments so you avoid underpayment penalties without over-paying early.

We explain the trade-offs in plain language and leave decisions to you. Where a position carries risk, we tell you and document the reasoning.

Tax preparation for non-resident and foreign-owned businesses

International founders often assume that having no US residency means having no US filing duties. That is not always true. A US LLC or corporation is a US entity even when every owner lives abroad. A foreign-owned single-member LLC is generally treated as a disregarded entity for income tax but must still file Form 5472 and a pro forma Form 1120 each year, and the penalty for failing to do so begins at $25,000 per form. Start with our Form 5472 guide, and read what happens after a missed deadline in late filing penalties.

Whether a non-resident owner owes US income tax depends on whether income is effectively connected with a US trade or business, whether it is US-source fixed or determinable income that can be subject to withholding, and whether a tax treaty applies. Many service businesses run entirely from abroad owe little US income tax, but they still need correct filings. Our article on whether non-residents pay US tax on LLC income explains the main cases.

Owners with accounts abroad may also have FinCEN reporting. A US person with foreign financial accounts whose combined value exceeded $10,000 at any time in the year files an FBAR, which is covered in our FBAR guide. Our cross-border compliance team handles these filings together, so that nothing is missed between the forms.

Our tax preparation process

We keep the process the same each year so you always know what happens next.

• Intake: we confirm your entity, owners, states, accounting method and any changes since last year.
• Document collection: you upload bank statements, payroll reports, 1099s, K-1s and loan or asset records to a secure portal, using a checklist we provide.
• Books review: we reconcile and adjust the records, and resolve open items with you, so the return starts from clean numbers.
• Preparation: federal and state returns are drafted, with a summary of tax owed, refunds and carry-forwards.
• Second review: a different accountant checks calculations, elections and supporting schedules.
• Signature and filing: you approve and e-sign, and we file and send confirmations.
• After filing: we help with IRS or state notices, amended returns and next year's estimated payments.

Who benefits most from outsourced tax preparation

Outsourced preparation suits owners who want accuracy without building a finance department. It works well for solo founders who have outgrown software, for startups preparing for diligence, for ecommerce sellers who sell across states, for owners with employees or contractors, and for non-US founders who need a team that understands both systems. If you also need monthly books, pairing tax with bookkeeping removes the year-end scramble, and adding payroll keeps withholding and wage reporting consistent.

Businesses that are forming or restructuring can start earlier. Our company formation service sets up the right structure and EIN, and our non-resident LLC guide explains the steps. Once the entity is active, the tax calendar starts, so it helps to have a preparer in place from the first year.

Common tax preparation mistakes we help you avoid

• Mixing personal and business spending, which weakens deductions and can complicate an audit.
• Missing information returns such as Form 5472, FBAR, 1099-NEC and W-2 because no one owned the calendar.
• Choosing an entity for the wrong reason, such as a low state fee, without reviewing tax effects.
• Paying estimated tax late or in the wrong amount and incurring underpayment penalties.
• Ignoring sales tax once sales cross a state's economic nexus threshold.
• Filing late because records were incomplete, then paying penalties that careful bookkeeping would have prevented.

Most of these are process problems, not knowledge problems, which is why fixed monthly processes matter more than any single filing.

Frequently asked questions

How much does tax preparation cost? Fees depend on the entity type, the number of states, the number of owners and the complexity of the books. We quote a fixed fee after a short scoping call, so there are no hourly surprises.

Can you take over from my previous preparer? Yes. We review prior-year returns, identify issues and set up a clean filing calendar. If prior filings were missed, we discuss the options for correcting them.

Do you file extensions and amended returns? Yes. We file extensions when records or deadlines require it and prepare amended returns when an error or new information changes a prior filing.

How long should I keep tax records? A common guideline is at least three years from filing, and longer for records that support assets, loans or losses carried forward. We store your filed returns in your portal for easy retrieval.

To discuss your return, book a free consultation and tell us your entity type and states. We will confirm the forms you need and give you a fixed-fee quote.

Documents to gather before your return

• Prior-year federal and state returns and any IRS or state notices.
• Profit and loss statement, balance sheet and general ledger from your books.
• Bank, credit card and loan statements for every account used in the business.
• Forms 1099-NEC, 1099-K, 1099-INT, W-2 and Schedule K-1 received.
• Payroll reports, quarterly filings and records of estimated payments made.
• Asset purchase invoices, vehicle logs and home-office details where deductions apply.
• Ownership records, operating agreement and details of owner contributions, loans and distributions.

Sending these early gives us time to resolve questions before the deadline, and it usually lowers the cost of preparation.

State taxes and sales tax nexus

State rules differ more than most owners expect. Some states tax pass-through income at the entity level, some require composite or non-resident withholding, and some charge minimum franchise taxes regardless of profit. A business that sells online can also create sales tax collection duties in states where it has no office, once its sales or transaction count passes that state's economic nexus threshold.

We review where your customers, employees, inventory and contractors are located, map the states that may claim tax and prepare returns for those that apply. If you have uncollected sales tax from prior periods, we help you assess the exposure and the options for registering and filing going forward.

Responding to IRS and state notices

A notice is not always bad news, but it does have a deadline. Notices may ask for information, propose an adjustment or bill a penalty. We read the notice, compare it with your filed return and prepare a response with support. Where the IRS is right, we explain the fix. Where it is wrong, we document the correction. Prompt, organized replies often resolve matters quickly.