The Seven Payroll Mistakes That Trigger IRS Notices, And How To Avoid Them

Payroll is deceptively simple. Pay the employee, withhold the taxes, deposit them with the government. Most businesses run through that loop hundreds of times before they encounter a problem. By the time the problem shows up as a notice from the IRS or a state department of revenue, it has often been compounding for months.

Here are the seven mistakes we see most often, and the simple operating fix for each.

1. Misclassifying Employees as Contractors

The single most expensive payroll mistake. The IRS uses a 20-factor test to determine worker classification, but the practical question is whether you control how and when the work is done. If you do, the worker is almost certainly an employee.

Misclassification penalties include back payroll taxes, interest, and a 100% penalty on the unwithheld amount. State penalties stack on top. We have seen settlements exceed six figures for businesses with as few as five misclassified workers.

The fix: if you direct the work, the person is an employee. If in doubt, file Form SS-8 with the IRS for a determination, or just classify as W-2. The cost of being slightly overcautious is dramatically lower than the cost of being wrong.

2. Missing Federal Payroll Tax Deposits

Federal payroll deposits are due either monthly or semi-weekly depending on your lookback period. The penalty for a 16+ day late deposit is 10%. The penalty for not depositing at all and waiting for the IRS to notice is 15%, plus interest, plus a potential trust fund recovery penalty against the responsible party personally.

The fix: if you are still doing payroll manually or through a system that does not auto-pay federal deposits, switch providers. Gusto, ADP, Paychex, Rippling, and others handle this automatically.

3. Failing to Withhold State Taxes Where Employees Work

If you have an employee who lives in one state but works in another (or works remotely from a state different from your office), you may have nexus and withholding obligations in their state. Many businesses get this wrong by withholding only in the state where they are headquartered.

The fix: at hire, ask each employee where they physically perform their work. If it differs from your home state, register for payroll tax accounts in that state immediately. Most states have ten to thirty day windows to register after the first day of work.

4. Late 1099-NEC Filings

1099-NEC forms for contractor payments of $600 or more are due to the recipient and the IRS by January 31. Penalties scale with how late you file: $60 per form within 30 days, $130 within mid-August, $330 after, and up to $660 per form for intentional disregard.

The fix: collect a W-9 from every contractor before issuing the first payment, never wait until year-end. Use a payment system (Bill.com, Gusto contractor payments) that tracks 1099-eligible payments automatically.

5. Incorrect S-Corp Owner Compensation

S-corp owners often try to take all earnings as distributions to avoid payroll tax. The IRS standard is that owner-employees must take "reasonable compensation" as W-2 wages, which is then subject to payroll tax. The reasonable compensation must be supported by what someone in a similar role would earn at arm's length.

If audited and the IRS reclassifies distributions as wages, you owe back payroll tax, penalty, and interest, often retroactive to the original tax year.

The fix: document reasonable compensation annually. Use industry benchmarks (RC Reports, BLS data, salary surveys). The general rule is to pay yourself at least enough to look defensible if examined.

6. Mishandling Bonus and Commission Withholding

Bonus and commission payments have specific withholding requirements. The supplemental wage withholding rate is 22% for federal (37% above $1M annually). Many businesses default to regular wage withholding on bonuses, which can dramatically under-withhold and surprise employees at tax time.

The fix: use a payroll provider that handles supplemental wage rules automatically. Verify on the first bonus run that the withholding matches IRS rules.

7. Not Reconciling Year-End Wages to W-2s

At year-end, your total wages on Form 941 (quarterly) and Form 940 (annual FUTA) should match the totals on the W-2s you issue. Many businesses discover that they don't, often because of bonus runs, retro pay, or third-party sick pay that was not properly recorded in payroll.

The fix: reconcile Q4 941 totals to W-2 totals before issuing W-2s, not after. Build a December-31 close checklist that includes this reconciliation as a required step.

The Common Thread

Every mistake on this list shares a single root cause: payroll being treated as a transaction rather than a system. Run individually, every payroll is simple. Operated as a system with controls, none of these mistakes happen. Operated reactively, every one of them will happen eventually.

If you would like to put payroll on autopilot with the controls and reconciliation discipline that prevents these errors, our team can take it over for you, integrated with your monthly bookkeeping and tax planning.