Understanding Business Tax Basics

Most new business owners get their first real shock at tax time, not because the rate is a mystery, but because nobody warned them how the timing and the paperwork actually work. Maria spent her first year running a landscaping LLC focused entirely on winning clients and keeping the mowers running. She turned a healthy profit, twenty thousand dollars more than she expected, and assumed the extra would just sit in her account until she filed the following April. Instead she owed a four figure penalty for not paying anything toward that profit along the way, on top of the tax itself. Nothing about her situation was unusual. This module covers the basics so the same thing does not happen to you: what you actually owe, when you owe it, and where a little planning during the year saves real money and stress later. It is an overview, not tax advice. Tax law varies by state and changes most years, so treat this as the map, not the final word for your specific situation, and confirm anything that matters with a CPA or irs.gov before you act on it.

If you are self-employed or run a default-taxed LLC, you pay self-employment tax of 15.3 percent on your net business income: 12.4 percent for Social Security and 2.9 percent for Medicare. A regular employee only pays half that combined rate, 7.65 percent, because their employer quietly pays the other half, and it never shows up on a pay stub as a separate cost. When you are self-employed, there is no separate employer to split it with, so you owe both halves yourself, billed to you directly instead of disappearing before you ever see the money. This is the single most common shock new founders describe: on eighty thousand dollars of net profit, self-employment tax alone runs roughly twelve thousand two hundred forty dollars, before a dollar of income tax is even calculated on top of it. The good news is that half of what you pay in self-employment tax is itself deductible from your income tax, and an S-Corp election can reduce the amount subject to this tax in the first place once your profit is high enough to justify the extra paperwork. For the full mechanics of how that works, including when it actually pays for itself, see S-Corp vs. LLC: Taxes & How Owners Get Paid.

Employees have tax withheld from every paycheck automatically, so by April they have usually already paid in close to what they owe. Self-employed people do not have anyone doing that for them, so the IRS expects you to pay estimated taxes four times a year instead of settling up in one lump sum the following spring. This is the same pay-as-you-go logic behind payroll withholding generally (see the Hiring module): the system is built to collect tax close to when it is earned, and underpaying during the year can trigger a penalty even if you pay the full balance by the April deadline. Jordan, a freelance graphic designer, learned this the expensive way in her second year: she paid her entire tax bill in full, on time, on April 15, exactly like she had as an employee, and still owed a penalty, because the IRS measured whether she had paid enough throughout the year, not just by the deadline.

Legitimate business expenses reduce your taxable income, which is why keeping track of them is worth real money, not just tidiness. The common categories most businesses run into are a home office (specific square footage and exclusive use rules apply), the business share of a phone and internet bill, software and subscriptions, business travel, professional development and courses, equipment and tools, advertising, self employed health insurance premiums, and retirement contributions through a SEP-IRA or Solo 401k.

The rule that governs all of it is that an expense has to be ordinary and necessary for your type of business. Ordinary means common and accepted in your industry: a laptop is ordinary for a consultant, a commercial oven is ordinary for a bakery. Necessary means helpful and appropriate for your business, not that it was strictly required to keep the doors open. Tom runs a one person bookkeeping practice and tried to deduct a boat he used maybe twice a year to entertain a couple of clients. That expense fails the test on both counts: a boat is not ordinary for a bookkeeping business, and entertaining two clients twice a year does not make it necessary either. This is a real legal standard the IRS applies whenever a deduction gets questioned, not just a rule of thumb, so the honest question for anything you are about to expense is whether another business owner in your field would recognize it as a normal cost of doing business.

Different business structures are taxed differently, and the choice has real cash consequences well beyond liability protection, covered in full depth in the Business Structures and S-Corp vs. LLC modules. The short version: a sole proprietor or single-member LLC reports business income directly on Schedule C of their personal return, with no separate business filing at all. A multi-member LLC or partnership files a partnership return, Form 1065, and profit passes through to each partner's personal return in proportion to their ownership. An S-Corp files its own corporate return, Form 1120-S, and its owners are paid a salary, subject to normal payroll tax, plus distributions on top of that salary, which are not. A C-Corp pays corporate tax on its profit first, and then owners pay personal tax again on any dividends they receive from what is left, a pattern known as double taxation. That second layer is exactly why most small businesses that are not raising venture capital or planning to go public avoid the C-Corp structure entirely: the same dollar of profit gets taxed twice before it ever reaches the owner's pocket.