How to Set Up Section 125 Pre-Tax Deductions in ADP

ADP processes payroll for millions of employees across the United States, making it one of the most widely used platforms for managing compensation and deductions. If you’re implementing a Section 125 cafeteria plan, ADP has built-in functionality to handle pre-tax deductions—but you need to set it up correctly from the start. This guide walks you through the process, from initial configuration to ongoing management.

Why ADP and Section 125 Work Well Together

ADP’s payroll platform is built to handle the complexity of pre-tax deductions. Section 125 cafeteria plans require precise tax calculation—your employees’ federal withholding, Social Security, Medicare, and state taxes all need to be computed on a reduced gross income after pre-tax deductions are taken. ADP automates this calculation, so you don’t have to manually adjust gross pay for each employee every payroll cycle.

Another advantage: ADP has integrations with many Third-Party Administrators (TPAs) who manage Section 125 plans. In many cases, enrollment data flows directly from your TPA into ADP, eliminating manual data entry and reducing errors.

Workforce Now vs. ADP Run: Which Interface Do You Use?

ADP offers two main payroll platforms, and the setup process varies slightly between them.

ADP Workforce Now is the cloud-based, modern interface. It’s designed for companies of any size and offers a comprehensive HR and payroll experience. If you’re a newer ADP customer or recently migrated, you’re likely using Workforce Now. The interface is more intuitive, and most new features land here first.

ADP Run (formerly ADP eTime) is the traditional, browser-based interface. Many established clients still use this platform, especially if they’ve been with ADP for several years. While it’s being phased out in favor of Workforce Now, it remains fully functional.

Whichever platform you use, the conceptual steps are the same—you’re creating a pre-tax deduction code and assigning it to employees. The navigation paths differ, but the underlying logic is identical. If you’re unsure which platform you’re on, check your login page or call ADP support.

Step-by-Step Setup Process

Step 1: Prepare Your Plan Document

Before you touch ADP, you need a signed Section 125 plan document in place. For details on what goes into this document, see Section 125 Implementation Guide. This document outlines the rules of your cafeteria plan—what benefits employees can elect, any nondiscrimination restrictions, and how the plan operates.

Your TPA provides this document. If you don’t have a TPA yet, you’ll need one to administer your Section 125 plan legally. The TPA is responsible for ensuring your plan complies with IRS regulations, handling employee elections, and providing year-end compliance reporting. Don’t skip this step. You can’t simply set up pre-tax deductions in ADP without a valid plan document in place.

Once you have the document, share it with your ADP administrator or payroll team. They’ll need to reference it when setting up deduction codes.

Step 2: Create a Pre-Tax Deduction Code in ADP

Here’s what the process typically looks like when you or your payroll administrator sets this up. Knowing these steps helps you have an informed conversation with your ADP rep or TPA.

In Workforce Now: Your administrator navigates to Payroll > Setup > Deductions, clicks Create Deduction, and fills out the details:

• Deduction Name: Something clear like “Medical Insurance Pre-Tax” or “Health Premium Pre-Tax”
• Deduction Type: Select “Pre-Tax” (not post-tax)
• Benefit Category: Choose the appropriate category (usually “Health/Medical” for health premiums, or “Dependent Care” for FSA/DCFSA)
• Effective Date: The date the deduction becomes active (typically the first day of the plan year or the date your Section 125 plan becomes effective)
• Tax Treatment: Ensure it’s set to reduce federal, Social Security, and Medicare withholding (and state taxes if applicable in your state)

In ADP Run: Go to Setup > Deductions > New Deduction. The process is similar—you’ll specify the deduction name, type, and tax treatment.

A critical detail: make sure the deduction is flagged as pre-tax for all applicable payroll taxes. Some misconfigurations only exclude the deduction from federal withholding but not from FICA taxes, which would be incorrect for a Section 125 deduction.

Step 3: Assign Deductions to Employees

Once the deduction code exists, you need to assign it to each employee who elected the benefit.

In Workforce Now: Go to Payroll > Employee File > [Select Employee] > Compensation. Add the deduction code and enter the deduction amount. This is typically the employee’s monthly premium amount (or monthly cost for other eligible expenses).

In ADP Run: Navigate to Employee File > Deductions and add the code with the corresponding amount.

Some HR teams do this manually for each employee. Others work with their TPA to upload a batch file of elections. If your TPA has a direct feed with ADP, deductions may be automatically populated after the open enrollment period closes.

Pro tip: Set an effective date that aligns with your plan year. If your plan year starts January 1 but elections are made in November, set the effective date for January 1, not the enrollment date. This ensures deductions don’t begin before the plan year actually starts.

Step 4: Set Effective Dates Correctly

This is where many HR teams stumble. Each deduction assignment needs an effective date. In most cases:

• Deductions for existing employees take effect on the plan year start date (typically January 1)
• Deductions for new hires take effect on their hire date or the first day of the plan month after they’re eligible (usually 30 days after hire)
• Changes made during open enrollment take effect on the plan year start date, not the enrollment date

ADP will calculate taxes on payroll based on the effective date of the deduction. If you accidentally set an effective date in the past, ADP may attempt to retroactively adjust previous paychecks—which can create a mess. If you set a future date, the deduction won’t take effect until that date.

Handling Common Scenarios

New Hires

When a new employee is hired, they’re typically eligible for pre-tax benefits either immediately or after a waiting period (often 30 days). You’ll need to:

1. Confirm their benefit elections (they should have completed enrollment paperwork)
2. Add the pre-tax deduction code to their employee profile in ADP
3. Set the effective date to the date they become eligible
4. Confirm their deduction amount matches their election

Terminations

When an employee terminates, their pre-tax deductions end. You’ll need to:

1. Remove or terminate the deduction code on their final paycheck date
2. If the termination happens mid-pay-period and they’ve already incurred the deduction, coordinate with your TPA on whether adjustments are needed
3. Confirm that year-to-date limits are properly reflected in your final paycheck to them

Open Enrollment Changes

During annual open enrollment, employees may change their elections. You’ll need to:

1. Update the deduction amounts in ADP to reflect new elections
2. Set the effective date to the plan year start date (or the first payroll after open enrollment closes, depending on your plan rules)
3. Ensure the old deduction code is terminated on the day before the new one takes effect

Mid-Year Qualifying Events

If an employee experiences a qualifying event (marriage, divorce, birth of a child, loss of coverage), they may change elections outside of open enrollment. Follow the same process as open enrollment changes, but set the effective date to the date the qualifying event occurred (or the date the election change is permitted under your plan document).

ADP’s Integration with Third-Party Administrators

If your TPA has a data feed with ADP, this is a major time-saver. Your TPA can send election data directly into ADP after open enrollment closes. However, this doesn’t mean you can ignore the setup—you still need to:

• Create the correct deduction codes in ADP (the feed matches elections to codes)
• Confirm the effective dates are aligned between your TPA’s records and ADP’s records
• Test the feed before the first payroll cycle to catch any mismatches

Ask your TPA if they have an ADP integration. If they do, ask for documentation on how to set it up and what you need to provide on your ADP side.

Troubleshooting: When ADP Support Doesn’t Get It

ADP support handles thousands of clients with varying benefit structures. Sometimes, when you call about pre-tax deductions and Section 125 setup, the support agent may not be familiar with cafeteria plan rules or may confuse pre-tax deductions with other types of deductions.

If this happens:

• Ask for a payroll specialist, not general support
• Be specific: Say “Section 125 pre-tax deduction” rather than just “pre-tax deduction” or “benefits deduction”
• Have your plan document handy: Reference specific sections if needed
• Ask about escalation: If the agent is unsure, ask them to escalate to a senior specialist or to ADP’s benefits team
• Document everything: Note the date, time, agent name, and what was discussed. If you need to follow up, you’ll have a reference point.

If ADP can’t solve the problem and it’s truly a payroll configuration issue, your TPA may be able to help. Many TPAs have trained specialists who know ADP inside and out.

Ongoing Management and Year-End Wrap-Up

Annual Limit Updates

Section 125 plans have annual limits set by the IRS. For 2026, the health insurance premium deduction limit is $23,500 (check the current year for the exact figure). When limits change, you’ll need to:

1. Update your plan document (your TPA handles this)
2. Review employee deductions in ADP to ensure no one exceeds the limit
3. Communicate any changes to employees

Rate Changes

When health insurance rates increase (typically annually), employees’ deduction amounts will change. You’ll need to:

1. Collect new election forms from employees during open enrollment (or notify them of changes if your plan allows automatic rate adjustments)
2. Update deduction amounts in ADP
3. Ensure effective dates are correctly set

Year-End Reporting

ADP generates W-2 reports and other tax documents. Your pre-tax deductions should automatically reduce the gross income reported on W-2s. Before finalizing year-end payroll:

1. Run a report of year-to-date pre-tax deductions by employee
2. Cross-check this against your TPA’s records
3. Confirm the amounts are reasonable and match election documents
4. Ensure no employee exceeded annual limits

Your TPA will provide a plan administration report showing all deductions taken and confirming compliance. Keep this on file for audit purposes.

The Bottom Line

Setting up Section 125 in ADP is straightforward once you understand the key concepts: you’re creating a deduction code, assigning it to employees, and setting effective dates. The real work comes in the ongoing management—staying on top of enrollment changes, new hires, terminations, and annual limit updates.

If you’re working with a TPA (which you should be), they’re your partner in this process. They ensure you stay compliant with IRS rules while ADP handles the payroll mechanics. Also consider setting up Section 125 in Paychex or Gusto if you’re evaluating payroll providers. Don’t hesitate to loop them in if you’re unsure about a configuration or scenario.

And remember: pre-tax deductions are a powerful benefit for your employees. Getting the setup right means they see the tax savings on every paycheck, which is one of the most concrete ways to show the value of your benefits package.