Payroll Deductions: The Employer's Guide

Every guide to payroll deductions tells you the same thing. There are mandatory ones and voluntary ones, there are pre-tax ones and post-tax ones, here is a list, here is how the arithmetic works.

All true, all useful, and all of it skips the question that actually determines whether you are breaking the law: by what authority are you taking this money?

Because a payroll deduction is not an arithmetic operation. It is a legal act. Somebody earned that money, it is theirs, and you are removing part of it before they ever see it. Doing that requires authority, and there are exactly three places authority can come from: a statute compels you, a court orders you, or the employee signed something. There is no fourth. And if you are deducting anything at all that does not sit in one of those three categories, you are not making a deduction. You are withholding wages without authorization, which in most states has a penalty attached that is considerably larger than the amount you took.

So this guide is payroll deductions from the angle nobody covers: what they are, the three sources of authority, what a valid written authorization actually has to contain, the document behind each individual deduction, and the priority order when there is not enough gross pay to satisfy everything. I build FirstHR, which is not a payroll processor. Your payroll system performs these deductions; what it cannot do is prove you were entitled to make them. That proof is a document, and it lives somewhere, and this article is largely about whether you can find it. General information, not legal advice, and deduction law is unusually state-specific.

What Payroll Deductions Are

A payroll deduction is any amount an employer withholds from an employee's gross pay before handing over what remains. What separates a lawful one from an unlawful one is not the amount and not the purpose. It is whether you had the right to take it.

Note the structure of that definition, because it is the whole article. Two independent questions. Mandatory versus voluntary is a question about authority. Pre-tax versus post-tax is a question about tax. They are not the same axis and a deduction has a position on each. A 401(k) contribution is voluntary and pre-tax. A garnishment is involuntary and post-tax. Confusing the two axes is why so many explanations of this topic feel muddled.

Payroll deduction, payroll deductions, deduction meaning

Same thing, singular or plural. What is worth separating is payroll deduction from payroll tax, because they are used interchangeably and are not the same.

A deduction comes out of the employee's money. A payroll tax includes the portion you pay on top, out of your own pocket, which never touches their wages and appears nowhere on their pay stub. Your matching 6.2 percent of Social Security is a payroll tax and is not a deduction from anybody. The distinction is not pedantry: it is the difference between money you are holding on someone else's behalf and money that is simply a cost of employing them.

The Three Sources of Authority

Here is the framework that should govern every deduction you make. Before the money comes out, you should be able to say which of three things gives you the right to take it.

The third row is where small businesses get into trouble, and they get into it with the best of intentions. An employee says yes to something in a conversation. You start deducting. Nobody objects, because nobody minds. And you have been making an unauthorized wage deduction for eight months without either of you noticing, because a verbal yes is not authority and the absence of a complaint is not consent.

Deductions a Statute Requires

These are the ones nobody has any choice about, including you. They come out of every paycheck and no consent is sought because none is relevant.

Per IRS Topic 751, the combined employee FICA rate is 7.65 percent, and you match that out of your own funds. The Additional Medicare Tax is the odd one: you must withhold it once the employee's wages pass $200,000 in a calendar year, and there is no employer match on it.

Federal income tax is the fourth statutory deduction and it is the one with a document behind it. It is driven entirely by the employee's Form W-4 and the current withholding tables in IRS Publication 15.

Deductions a Court Orders

These arrive in the post as legal documents, with deadlines, and they are not requests.

Two things to internalize about this category.

The cap is a percentage of disposable earnings, not of net pay. Those are different numbers, disposable earnings is the higher of the two, and applying the cap to net pay means under-withholding and being pursued for the shortfall by the creditor.

You cannot fire someone over a single garnishment. The CCPA prohibits discharging an employee because their wages were garnished for any one debt, no matter how many collection actions there were for it. That protection does not extend to a second, separate debt. But the first one is protected, and terminating over it is its own violation on top of whatever else is going on.

The defense against every trap in that table is a record made on the day the order arrives, while the envelope is still in your hand. The type, the dates printed on its face, and what else was already running for that employee are the facts the priority rules turn on later, and they are the facts nobody can reconstruct a year afterwards. The intake sheet for doing that lives in the garnishment guide, alongside the answer deadline that carries the real liability, because none of that is a deduction question and all of it decides what you are allowed to deduct.

Deductions the Employee Agreed To

Everything else. Health premiums, retirement, union dues, charitable giving, commuter benefits, the repayment of a loan you made them. These exist only because the employee said yes, and the entire question is what form that yes took.

Because the yes is your authority. It is the only thing standing between a lawful deduction and a wage claim, and a great many small employers are relying on a yes that would not survive being asked about.

The 401(k) deduction

A 401(k) deduction is a deferral the employee elects and you execute, so the signed deferral election is your authority and the plan document sets the boundaries. The IRS caps the employee side: elective deferrals are limited to $24,500 for 2026, with $8,000 more for employees 50 and over and $11,250 at ages 60 through 63.

Two things about it catch small employers out. The deferral lowers the income tax base and stays inside the Social Security and Medicare base, as the IRS states directly, so raising a contribution moves one line on the stub and leaves the other where it was.

The second is that the money stops being yours the moment you withhold it. Under 29 CFR 2510.3-102, deferrals become plan assets once they can reasonably be segregated from your general account, and a plan with fewer than 100 participants gets a safe harbor: deposit within seven business days of the payday and it counts as timely.

What a Valid Authorization Looks Like

The requirements vary by state and they converge enough that following the strict version everywhere is simply easier than tracking the differences.

North Carolina is a useful example of how specific a state can be. Per the NC Department of Labor, where the amount of a deduction is known in advance, the written authorization must be signed on or before the payday it applies to, must state the reason, and must state the actual dollar amount or percentage. Where the amount is not known in advance, such as a register shortage, the employer needs a further written notice of the actual amount, given at least seven days before the deduction.

Seven days of advance notice, in writing, of a specific amount, on top of a prior signed authorization. That is what one state requires to deduct forty dollars from a cash drawer. It is worth reading twice, because it is a fair indication of how seriously this is taken and how casually most small employers approach it.

Common Payroll Deductions

The full inventory, sorted by the only thing that matters, which is where your authority comes from.

Read down the authorization column. Almost everything says yes. The deductions that need no authorization are the taxes and the court orders, and those are precisely the ones a small employer never worries about, because the payroll system handles them automatically. Everything the employer actually chooses to do requires a document, and the document is the part that gets skipped.

Pre-Tax and Post-Tax

The second axis, and it is a question about tax rather than about authority. Whether a deduction is pre-tax or post-tax has nothing to do with whether you were allowed to make it.

And one piece of plumbing that a small employer can easily not know exists: a health premium is only pre-tax if it runs through a Section 125 cafeteria plan. If you are simply deducting a premium with no such plan in place, that deduction is post-tax, and both you and the employee are paying more tax than necessary. It is an hour with an accountant and it is worth having.

How deductions show up on the W-2

The deductions you took all year reappear in January in the shape of the W-2, and the boxes disagree with each other on purpose. Box 1 is wages after the deductions that reduced the income tax base. Boxes 3 and 5 are Social Security and Medicare wages, which a traditional deferral never reduced.

Box 12 is where the individual amounts get named. Per the IRS instructions for Forms W-2 and W-3, code D is elective deferrals to a 401(k), code AA is designated Roth contributions, code W is HSA contributions including what the employee elected through a cafeteria plan, and code DD is the cost of employer-sponsored health coverage.

Code DD is the one to watch, because it is not a deduction at all. It reports what the coverage cost, your share included, purely for information. Every January somebody reads that number as money taken out of their pay, and the question lands on whoever runs payroll.

How to Calculate Payroll Deductions

Payroll deductions are calculated in a fixed order, because each step changes the base the next step runs on. Gross pay, then the pre-tax deductions, then the taxes, then any garnishment, then the post-tax voluntary items. What survives is net pay.

Your payroll system performs this sequence for you. The reason to know it anyway is that nearly every argument you will ever have about a paycheck turns out to be an argument about which base a number was calculated on.

A worked example, from gross to net

Here is one biweekly paycheck run through that sequence. Gross pay of $2,400, a $150 health premium through a Section 125 plan, and 5 percent deferred to a traditional 401(k). The two tax-table lines are illustrative figures. Everything else is arithmetic you can check.

The two base rows are the point of the exercise. Income tax runs on $2,130 and FICA runs on $2,250, because a Section 125 premium leaves both bases while a 401(k) deferral leaves only one. The IRS treats qualified benefits under a Section 125 plan as generally outside FICA and income tax withholding alike.

What percentage of a paycheck goes to deductions

There is no average worth quoting, and quoting one to an employee is how you end up explaining why their check came out different. Only one part is fixed: 6.2 percent for Social Security up to the wage base and 1.45 percent for Medicare on everything. The rest moves with the W-4, the state, and what the employee elected.

For a real person it is arithmetic on a real stub: total deductions divided by gross pay, times one hundred. Run it twice, once for the taxes alone and once for everything. The gap between those two numbers is the part the employee chose, and therefore the part they can change.

The Document Behind Each One

Every deduction on a pay stub is the visible end of a piece of paper. Here is the mapping, and it is the most useful thing in this article.

The pattern is that the taxes and the court orders take care of themselves, because they arrive as documents whether you want them or not. The voluntary ones are the ones you have to generate, and they are the ones that end up living in an email thread, a filing cabinet, or nowhere at all.

Which is a records problem rather than a payroll problem, and it is the actual gap. Your payroll system executes the deduction; it does not hold the signed election that entitled you to make it. That document belongs in the personnel file, retrievable, for at least as long as the retention rules require.

When the Money Runs Out

Here is the situation almost no guide addresses, and it happens more often than you would expect: the employee has multiple deductions, several of them are court-ordered, and there is not enough gross pay to cover everything.

You cannot pay them all. So which ones happen?

The rule at the top of that stack is federal and it is precise. Per the guidance from the Administration for Children and Families, an IRS tax levy is the only deduction that takes precedence over child support, and only where the levy was entered before the underlying support order was established. Otherwise child support is withheld before all other garnishments, full stop.

And note the bottom of the stack, because it has a practical consequence you must plan for. Voluntary deductions come last. When the money runs out, it is the health premium that does not get taken, not the garnishment. Which leaves you with an unpaid premium, an insurer who still wants it, and an employee whose coverage is now in question.

That situation has to be decided in advance, in a written policy, calmly. Deciding it on the morning payroll is due, under time pressure, is precisely when an employer reaches for the obvious solution of taking a little extra out of the next check, which is a deduction they may well have no authority to make.

The State Law Overlay

Everything above is the federal floor. It is the least protective version of these rules that exists anywhere, and states build on top of it in ways that vary enormously.

The overpayment row is the one that reliably surprises people. You overpaid somebody by mistake. The money is obviously yours. The instinct is to take it back out of the next check, and in a number of states you may not do that without written authorization, which means your innocent error becomes your violation the moment you try to fix it unilaterally.

And the practical consequence of all this is that the rule that binds you is a property of where the employee physically works, not where you are incorporated. One remote hire across a state line introduces a rulebook you have not read.

The Unauthorized Deduction

What actually happens when you take money you had no right to take.

First, you owe it back. That much is obvious and it is the least of it.

Then the state wage payment law arrives, and this is where it gets expensive. Many of them provide for penalties on top of the amount, some for liquidated or multiple damages, and a great many for the employee's attorney fees. That last one is the mechanism. A twenty dollar deduction is not worth a lawyer's time. A twenty dollar deduction with a fee-shifting statute behind it very much is.

And there is a version of this that is worse still, which is a deduction from an exempt employee's salary. An exempt employee must receive a predetermined salary not subject to reduction based on the quality or quantity of their work. An improper deduction can destroy the exemption, which means the employee is now entitled to overtime, potentially retroactively, and potentially so is everybody else in the same job classification. The general rule for a business with no payroll specialist is that deductions from an exempt salary are a question to get advice on rather than to answer yourself.

Payroll Deduction Plans

A related term that means something more specific. A payroll deduction plan is a systematic arrangement in which an employee authorizes a recurring deduction to fund a defined program.

The common ones are a retirement arrangement such as a payroll deduction IRA, an employee stock purchase plan, a health savings account, or a savings bond program. What defines it is that it is voluntary, recurring, and authorized in advance, which distinguishes it from a one-off deduction and from anything a court compels.

An automatic deduction is the same arrangement seen from the payroll side. Once the election is on file the amount comes out every period with nobody re-approving it, which is convenient right up to the point the election goes stale. It is also why a revocation has to reach payroll rather than sit in somebody's inbox.

Worth knowing for a small employer because the payroll deduction IRA is one of the simplest retirement arrangements available: it requires no plan document and no employer contribution. You are essentially providing the plumbing for the employee to save, which is a meaningful benefit that costs you very little.

The Annual Deduction Audit

Everything above compresses into a short recurring task. Once a year, pull one pay stub for each type of employee and interrogate every line on it.

Work it line by line off an actual stub rather than from memory, and write the answers down as you go. The sheet below is the record of that pass: one row for every deduction line on the stub, and a second tab for what the pass turned up, because a gap needs a date and an owner against it rather than a mental note to sort it out sometime.

Common Mistakes

The thread through all of them is a single confusion: treating a deduction as an accounting entry when it is a legal act. An accounting entry needs to be correct. A legal act needs to be authorized, and those are separate tests, and you can pass the first while failing the second every single pay period for years.

Which produces the one question worth carrying away from this. Not is this deduction right. That is your payroll system's job and it is probably doing it fine. The question is: if this employee walked out tomorrow and disputed every line on their pay stub, could I produce the document that entitled me to take each one? If the answer is yes, the arithmetic will look after itself. If the answer is no, then it does not matter how correct the arithmetic was.

Frequently Asked Questions