How Do You Calculate Payroll For A Small Business

You hired someone. Maybe your first employee, maybe your fifth. Now you have to pay them correctly, on time, every single pay period, without triggering a tax problem that follows you for years. If you’re wondering how do you calculate payroll for a small business, you’re asking the right question at the right time, because the mechanics of payroll aren’t obvious until you’ve done them once.

Payroll comes down to three moves: track the hours or salary, calculate what’s owed before taxes, then apply the deductions and taxes that turn that number into an actual paycheck. Each step has a formula. None of them are complicated in isolation. What trips people up is doing all three correctly, every time, for every employee type, without a system to catch mistakes.

This guide walks through the real math: formulas, worked examples, actual dollar figures. Then it covers where small businesses lose the most money to mistakes, and how to tell when the math has outgrown what you should be doing by hand.

What Is Payroll and How Does the Calculation Actually Work?

Payroll is the process of paying your employees for the work they did, correctly and on schedule, while withholding and remitting the taxes the law requires. That’s the whole job. The complexity comes from the fact that “correctly” has a lot of moving parts: hours worked, pay rate, filing status, benefit elections, garnishments, and tax rates that shift every year.

Every payroll run follows the same three-part sequence you use to calculate payroll, no matter how many employees you have or what industry you’re in. First, you track hours worked (for hourly employees) or confirm the pay period (for salaried employees). Second, you calculate gross pay, the full amount earned before anything is subtracted. Third, you apply deductions and taxes to arrive at net pay, the amount that actually lands in your employee’s bank account. The rest of this guide walks through each of those three steps in detail, with real numbers.

What You Need Before Your First Payroll Run

Before you run payroll for the first time, get four things in place. You’ll need an Employer Identification Number (EIN) from the IRS, since you can’t report or deposit payroll taxes without one. You’ll need a completed Form W-4 from every employee, which tells you how much federal income tax to withhold. You’ll need a completed Form I-9 for each employee, confirming they’re authorized to work in the United States. And you’ll need to pick a pay schedule: weekly, biweekly, semimonthly, or monthly, since some states restrict which schedules are allowed for certain types of work.

Biweekly is the most common choice for small businesses. It lines up cleanly with a 52-week year (26 pay periods) and keeps processing frequency manageable without stretching pay periods too long for hourly workers who rely on regular cash flow.

How Do You Calculate Gross Pay for Hourly and Salaried Employees?

Gross pay is the full amount an employee earns before any tax or deduction comes out. It’s also where hourly and salaried employees start to look like two completely different math problems, because they are.

Gross Pay Formula for Hourly Employees

For hourly employees, the formula is: hours worked × hourly rate = gross pay. Anything over 40 hours in a single workweek gets paid at 1.5 times the regular rate under federal overtime rules, so the full formula becomes: (regular hours × hourly rate) plus (overtime hours × hourly rate × 1.5).

Say you have an employee who earns $22 an hour and worked 46 hours in one week. Their regular pay is 40 hours times $22, which is $880. Their overtime pay is 6 hours times $22 times 1.5, which is $198. Add those together and their gross pay for the week is $1,078.

Gross Pay Formula for Salaried Employees

For salaried employees, the formula is simpler on paper: annual salary divided by the number of pay periods equals gross pay. A biweekly schedule has 26 pay periods a year, so an employee earning $65,000 a year would have a gross pay of $65,000 divided by 26, or $2,500 per pay period.

The catch with salaried employees is overtime eligibility. Salaried does not automatically mean exempt from overtime. Whether an employee is exempt depends on their job duties and salary level under federal and state rules, not simply on how they’re paid, so don’t assume a salaried title protects you from overtime obligations.

What Deductions and Taxes Come Out of Gross Pay?

This is the step where most small business owners get nervous, because it’s the step where a mistake becomes an IRS problem instead of just an accounting error. It’s also the most mechanical step. Once you know the rates, applying them is arithmetic. This is where the gross pay vs net pay distinction stops being abstract and becomes the actual number on your employee’s pay stub.

Mandatory Payroll Taxes

Getting payroll taxes for small business operations right starts with knowing which taxes are mandatory and which rates apply this year. Every paycheck has federal income tax withheld, based on the employee’s Form W-4 and the current IRS withholding tables. Depending on where your business operates, you may also owe state and, in some cities, local income tax withholding.

On top of income tax, you and your employee each pay Social Security tax and Medicare tax, together known as FICA. The Social Security portion is 6.2% of wages, up to an annual wage base that changes every year (it’s $184,500 for 2026). The Medicare portion is 1.45% of wages, with no wage cap, plus an extra 0.9% on wages above $200,000 for a single filer ($250,000 if married filing jointly). Both the Social Security and Medicare rates are matched by the employer, meaning you pay an equal amount out of your own pocket on top of what you withhold from the employee. These thresholds move every year, so verify the current wage base against IRS guidance before you run payroll rather than relying on last year’s numbers.

Pre-Tax and Post-Tax Deductions

Beyond mandatory taxes, most paychecks include a mix of voluntary and mandatory payroll deductions. Pre-tax deductions, like health, dental, and vision premiums or a traditional 401(k) contribution, come out of gross pay before taxes are calculated, which lowers the employee’s taxable income. Post-tax deductions, like Roth retirement contributions or after-tax benefit elections, come out after taxes have already been calculated.

Order matters here. Calculate pre-tax deductions first, then apply payroll taxes to the reduced amount, then apply post-tax deductions and any mandatory withholding like wage garnishments or child support orders, which must be withheld regardless of what the employee has elected.

What Does a Full Payroll Calculation Look Like, Start to Finish?

Most guides describe gross pay and deductions separately and stop there. Here’s what it looks like, start to finish, for one hourly employee and one salaried employee, using real numbers.

Take Maria, an hourly employee earning $24 an hour who worked 42 hours in the pay period. Her gross pay is 40 hours times $24 ($960) plus 2 overtime hours times $24 times 1.5 ($72), for a total of $1,032. From there, $60 comes out pre-tax for health insurance, leaving $972 in taxable wages. Federal income tax withholding, based on her W-4, comes to roughly $97. Social Security takes 6.2% of that taxable amount, or about $60.26. Medicare takes 1.45%, or about $14.09. State income tax withholding will vary by state, so we’ll set it aside here. After her health premium and all withholding, Maria’s net pay comes to approximately $800.65.

On the employer side, you owe a matching $60.26 for Social Security and $14.09 for Medicare, the same amounts withheld from Maria’s pay. You also owe FUTA, the federal unemployment tax: 6.0% on the first $7,000 of her wages for the year, though most employers who pay state unemployment tax on time receive a 5.4% credit that brings the effective rate to 0.6%, capping the federal portion at $42 per employee for the entire year, not per paycheck. State unemployment insurance is calculated separately and varies significantly by state and by your specific experience rate.

Now take David, a salaried employee earning $78,000 a year on a biweekly schedule. His gross pay per period is $78,000 divided by 26, or $3,000. He contributes $150 pre-tax to a 401(k), leaving $2,850 in taxable wages. Federal withholding comes to roughly $340. Social Security takes 6.2% of $2,850, or $176.70. Medicare takes 1.45%, or $41.33. After his retirement contribution and all withholding, David’s net pay is approximately $2,291.97.

Your true cost as the employer isn’t David’s $3,000 gross pay. It’s $3,000 plus your matching FICA of $218.03, plus your share of unemployment insurance, plus any employer contribution you make toward his benefits. That gap between gross pay and your actual cost is one of the most common places small business owners underestimate their payroll calculation steps and get surprised by their true labor costs at tax time.

What Payroll Mistakes Cost Small Businesses the Most?

Most small business payroll mistakes cluster around three predictable spots, and all three are expensive.

Misclassifying an employee as an independent contractor is the costliest. If the IRS determines a worker should have been a W-2 employee, you’re liable for back taxes plus penalties, even if the mistake was unintentional. Under IRS rules for unintentional misclassification, you’re looking at roughly 1.5% to 3% of the wages paid (depending on whether you filed the required 1099s), 20% to 40% of the employee’s share of FICA taxes, and 100% of your own employer share of FICA, with interest accruing on top of all of it. If the IRS decides the misclassification was intentional, those reduced rates disappear entirely and you owe the full amount plus steeper penalties.

Late tax deposits are the second big one, and the penalty scales fast. The IRS failure-to-deposit penalty starts at 2% for a deposit that’s one to five days late, jumps to 5% for six to fifteen days late, climbs to 10% for anything later than that, and reaches 15% once the IRS has sent a notice and you still haven’t paid. On a $15,000 deposit, that’s the difference between a $300 penalty and a $2,250 one, for the same missed payment, just discovered later.

Incorrect withholding from outdated tax tables rounds out the list. Tax brackets, wage bases, and withholding tables update annually, and running payroll off last year’s numbers, even by accident, means every paycheck you process is slightly wrong until you catch it. Fixing it after the fact means correcting past pay stubs, filing amended returns, and in some cases reissuing W-2s.

None of these mistakes require negligence. They require running payroll on autopilot for one pay period too many without checking your numbers against current guidance.

When Does It Make Sense to Calculate Payroll Yourself vs. Use a Payroll Service?

Manual payroll works for a genuinely small, simple team: one or two employees, stable hours, no multi-state complexity, no frequent overtime. If that’s your business, doing the math yourself with a spreadsheet or basic software is a legitimate, low-cost option, and there’s no reason to feel like you’re cutting corners by choosing it.

The signals that it’s time to hand payroll off usually show up gradually, then all at once. You’ve grown past a handful of employees. You’re now hiring across more than one state, which means tracking a second, or third, set of tax rules. Overtime and benefit deductions have become frequent enough that the calculation isn’t quick anymore. Or you’ve already missed a deposit deadline once, and you know the failure-to-deposit penalty schedule only gets worse if it happens again.

None of this is a judgment on your ability to do the math. It’s a question of whether the time and risk still make sense at your current size. Manual payroll error rates run higher than most owners assume, commonly cited between 1% and 8% of processed payroll, and on even a modest annual payroll, that adds up to real money in corrections, amended filings, and employee trust. Weigh that against what outsourced payroll actually costs: most small business payroll services run somewhere in the range of $150 to $300 a month for a team under 25 employees, often landing well under what a single missed deposit penalty or a single misclassification correction would cost you.

Let Milestone Take Payroll Calculations Off Your Plate

Even a payroll process you’ve built correctly still takes real time every pay period: tracking hours, rerunning the math, double-checking this year’s tax tables, watching deposit deadlines. That time adds up whether you have three employees or thirty.

Milestone’s payroll services handle the calculation, filing, and compliance side of payroll so you’re not re-verifying your own math every pay period. Our team works across SaaS companies, law firms, healthcare practices, and agencies, the kinds of small businesses that need payroll done right without having to become in-house payroll experts to get there. If you’re ready to stop double-checking your own numbers, visit Milestone’s payroll services page to see how we handle it.

Frequently Asked Questions About Calculating Payroll for a Small Business

What’s the difference between gross pay and net pay?

Gross pay is the full amount an employee earns before anything is withheld. Net pay is what’s left after taxes, benefit premiums, and any other deductions come out. The gross pay vs net pay gap is made up of federal and state taxes, FICA, and whatever pre-tax or post-tax deductions apply to that employee.

How do you calculate payroll for yourself as the business owner?

How you pay yourself depends on your business structure. Owners of sole proprietorships and single-member LLCs typically take an owner’s draw rather than running payroll for themselves, while S corporation owners who work in the business are usually required to pay themselves a reasonable W-2 salary through regular payroll. If you’re not sure which applies to you, confirm it with a CPA before your first pay period, since getting it wrong has tax consequences beyond payroll itself.

How often should you pay employees, weekly, biweekly, or monthly?

Biweekly is the most common pay schedule for small businesses because it balances manageable processing frequency with steady cash flow for employees. Some states set minimum pay frequency requirements by law, so check your state’s rules before choosing, since nonexempt hourly employees are sometimes required to be paid more often than monthly.

Do you need payroll software if you only have one or two employees?

Not necessarily, but it helps more than most owners expect. Even with one or two employees, manual calculations still require you to track current tax tables, wage bases, and deposit deadlines correctly every single pay period, and a missed deadline carries the same penalty percentage regardless of your headcount.

How much does a payroll service typically cost for a small business?

Most small business payroll services charge a monthly base fee plus a per-employee fee, and full-service pricing for a small team commonly falls between roughly $150 and $300 a month, all in. The exact cost depends on your employee count, pay frequency, and whether you need multi-state filing or added HR support.