Last updated: March 2026

Union payroll: how to process it without costly mistakes

Union payroll has more ways to go wrong per paycheck than any other type of payroll in construction. Every union trade has its own collective bargaining agreement with its own wage rates, fringe benefit contribution rates, overtime rules, and reporting deadlines. Miss a fringe contribution by three days and you owe a late payment penalty to the fund. Misclassify a journeyman as an apprentice and you owe back wages plus liquidated damages. Report the wrong classification on a certified payroll submission and the general contractor pulls you off the project. I have seen a single misclassification on a prevailing wage job cost a subcontractor $38,000 in back pay and penalties.

What makes union construction payroll different

Standard payroll calculates gross pay, withholds taxes, and deposits a net check. Union payroll does all of that plus a second layer of calculations that standard payroll software was never designed to handle.

Fringe benefit contributions. The collective bargaining agreement specifies employer contributions to the union health and welfare fund, pension fund, annuity fund, training fund, and sometimes a vacation fund. These are calculated per hour worked, not as a percentage of wages. A carpenter's CBA might require $12.50 per hour to health and welfare, $8.00 per hour to pension, $6.00 per hour to annuity, and $1.50 per hour to training. On a 40 hour week, that is $1,120 in fringe contributions on top of the hourly wage. The contributions are the employer's obligation. They are not withheld from the worker's pay.

The tradeoff is significant. A union carpenter earning $45 per hour in base wages actually costs the employer $73 per hour when fringe contributions are included. Construction payroll budgeting that looks only at the wage rate underestimates true labor cost by 40% to 60%. Contractors who bid jobs without calculating the fringe load lose money on every union project they win.

Every dollar of fringe contribution is invisible on the worker's pay stub but visible on the contractor's profit margin.

Multiple rate structures on the same job. A single construction project can have electricians under IBEW rates, plumbers under UA rates, carpenters under UBC rates, and laborers under LIUNA rates. Each trade has different base wages, different overtime triggers, different fringe contribution rates, and different fund reporting deadlines. Federal overtime rules under the Fair Labor Standards Act still apply, but the CBA may set a lower overtime threshold for certain classifications. Your payroll system must track each trade separately or the fund remittance reports will not balance.

When this is wrong: contractors who process union payroll through standard small business payroll software like Gusto or basic Paychex. These platforms do not support per-hour fringe calculations, multi-fund remittances, or union classification tracking. They work for the contractor's non-union office staff. They fail on the field crew. Construction payroll companies that specialize in union work use platforms built specifically for this, including Foundation Software, Viewpoint, and Sage 300 CRE.

Prevailing wage and the Davis-Bacon layer

On federally funded construction projects, the Davis-Bacon Act requires contractors to pay prevailing wage rates as determined by the Department of Labor. Prevailing wages include both a base hourly rate and a fringe benefit rate for each trade classification. The rates are published by the DOL and vary by county and trade.

On a prevailing wage job, you must pay at least the published base rate in cash wages. The fringe portion can be paid as cash wages, contributed to bona fide benefit plans, or split between the two. Most union contractors satisfy the fringe requirement through their existing CBA contributions. Non-union contractors on prevailing wage jobs must either pay the fringe rate as additional cash wages (which increases FICA, unemployment, and workers comp obligations) or set up qualifying benefit plans that absorb the fringe amount.

The gotcha is the classification match. The DOL prevailing wage determination lists specific trade classifications with specific rates. If you list a worker as "Carpenter" on the certified payroll but the DOL determination uses "Carpenter, Building Construction" versus "Carpenter, Heavy/Highway Construction" at different rates, and you use the wrong one, you have underpaid every hour that worker was on the project. The DOL does not accept "close enough." The classification on your certified payroll report must match the determination exactly.

State prevailing wage laws add another layer. Many states have their own prevailing wage requirements for state-funded projects, with rates that differ from the federal Davis-Bacon rates. A project receiving both federal and state funding may require compliance with both sets of rates, using whichever is higher for each trade. Tracking which rate applies to which funding source on a blended project is where most construction payroll errors originate.

Certified payroll reporting on union jobs

Contractors on prevailing wage projects must submit weekly certified payroll reports using Form WH-347 or an equivalent format. The report shows every worker's name, trade classification, hours worked each day, hourly rate, gross pay, deductions, and net pay. The contractor signs a statement of compliance certifying that the wages are correct and that no rebates or kickbacks occurred.

The reports are due weekly. Not biweekly. Not when you get around to it. Weekly, covering the prior work week. Late submissions can trigger a notice from the GC, and repeated late filings can result in removal from the project. On federal projects, the DOL can debar a contractor from future federal work for willful violations of certified payroll requirements.

One late certified payroll report can get you pulled from a project faster than one bad weld.

Most standard payroll software does not generate WH-347 reports. Subcontractor payroll on prevailing wage jobs requires either a construction-specific payroll platform that produces the reports automatically or a manual process where someone extracts the data from payroll and formats it into the WH-347 template. Manual preparation takes 30 to 60 minutes per week per project and introduces transcription errors that the GC's compliance team will catch.

When this is wrong: contractors who submit certified payroll reports based on estimated hours and then reconcile later. The certification is a legal statement that the numbers are accurate as of the submission date. Filing inaccurate reports, even with the intention to correct them later, is a compliance violation. Reconcile first, certify second.

Workers comp on union payroll

Workers comp for construction trades carries some of the highest workers comp class code rates in the industry. A roofer under class code 5551 can cost $20 to $30 per $100 of payroll depending on the state. The workers compensation insurance premium on union construction payroll is calculated on total remuneration, which includes base wages, overtime at straight time value, and in some states, certain fringe benefit contributions.

The experience modification rate multiplies everything. A union contractor with an EMR of 1.25 pays 25% more than the base rate on every dollar of payroll. On a $2 million annual payroll under high-risk class codes, that 0.25 multiplier adds $50,000 or more in annual workers comp premium. Union safety programs, return-to-work protocols, and claims management directly affect the EMR, which is why large union contractors invest heavily in safety.

The tradeoff for union contractors: union workers tend to be better trained and have lower injury rates than non-union workers in the same trades, which pushes the EMR down over time. But the base rates for construction class codes are so high that even a favorable EMR still produces significant workers comp cost per employee. A union electrician with a clean safety record might cost $6 per $100 of payroll in workers comp. The same electrician working non-union at the same rate costs the same $6. The union premium is not higher because the worker is union. It is the same because the risk is the same.

Common union payroll mistakes

Paying fringe contributions late. Union funds assess late payment penalties starting the day after the due date. Penalties range from 5% to 20% of the contribution amount depending on the fund. A $15,000 monthly fringe remittance that arrives two days late can generate a $750 to $3,000 penalty. Set calendar reminders for every fund's due date. They are not all the same.

Fund due dates are not standardized and rarely match your payroll schedule.

Confusing apprentice rates with journeyman rates. Apprentices earn a percentage of the journeyman rate based on their period of apprenticeship. A first-year apprentice might earn 50% of journeyman scale. A fourth-year might earn 85%. Paying an apprentice the wrong period rate underpays them on every hour worked. The fund audits catch this, and the back pay obligation plus penalties falls on the contractor. When this analysis breaks down: open shop projects where the contractor sets their own apprentice pay scales without a CBA. The fund audit risk disappears, but the DOL prevailing wage classification requirements still apply if the project is federally funded.

Failing to track travel time and show-up time correctly. Many CBAs require pay for travel time to remote job sites and guarantee minimum hours (typically four) if a worker reports to the site and is sent home due to weather or project delays. Contractors who do not pay show-up time owe back wages for every occurrence.

Using the wrong overtime rules. Federal law requires overtime after 40 hours in a week. Some state laws require daily overtime after 8 hours. Some union agreements require overtime after fewer hours or on specific days regardless of total weekly hours. California union construction workers may be entitled to daily overtime under state law AND weekly overtime under the CBA, using whichever produces the higher pay for each day. Running time and a half on the wrong trigger shortchanges workers and creates a wage claim.

What to do this week

Pull every active CBA for trades working on your current projects. Verify that the wage rates, fringe contribution rates, and fund remittance deadlines in your payroll system match the current agreement. CBAs are renegotiated periodically, and rate changes take effect on specific dates. If your system is running last year's rates, every paycheck since the effective date is short.

Check your last three months of fund remittance reports against the actual payments sent. Confirm every payment arrived before the due date. If any were late, calculate the penalty exposure and contact the fund to negotiate before they assess it.

If you are bidding prevailing wage work and currently using standard payroll software, get a quote from a construction payroll company that handles certified payroll reporting and prevailing wage compliance. The cost of specialized construction payroll software is $200 to $500 per month. The cost of a single prevailing wage violation is $10,000 to $50,000. The math is clear.

Written by a Certified Payroll Professional with 30 years of experience.

This is not legal or financial advice. Consult a qualified professional for your specific situation.