ACA reporting has a way of staying quiet until it isn't. You file your 1095-C forms, the year closes, and months later a letter shows up from the IRS with a proposed penalty attached. By then the error that caused it is buried in last year's data, and you're reconstructing offer-of-coverage decisions you made a year ago for people who may not even work there anymore. If that scenario makes your stomach drop, you're not alone. ACA reporting is one of the most common reasons payroll and HR leaders call us with their hair on fire.
The good news: most 1095-C penalties come from a short list of preventable mistakes. They aren't exotic. They're coding slips, eligibility tracking gaps, and data that didn't get cleaned up before filing. ADP SmartCompliance can carry a lot of the load, but the system reports what you tell it. If the inputs are wrong or the setup doesn't match how your workforce actually behaves, the output goes out wrong too.
This post walks through what 1095-C reporting requires, where the mistakes tend to hide, and how to catch them before the IRS does. Treat this as general guidance to get oriented, then confirm specifics with your licensed tax advisor or ADP representative. The rules and dollar thresholds change, and your situation is yours.
If you're an Applicable Large Employer (generally 50 or more full-time and full-time-equivalent employees), the 1095-C is how you tell the IRS what coverage you offered to each full-time employee, month by month. It answers three questions for every covered month: Did you offer coverage? Was that coverage affordable and did it meet minimum value? And was the person actually enrolled?
That last point trips people up. The 1095-C reports the offer, not just enrollment. An employee who declined your plan still gets a form if they were full-time, because the IRS wants proof you made a qualifying offer. Miss that and the agency can't tell whether you met your obligation, which is exactly the kind of gap that draws a penalty notice.
The form has three parts. Part I is employee and employer identifying information. Part II is the heart of it, where the offer-of-coverage codes live. Part III only applies if you self-insure and reports who was actually enrolled. Most penalty risk concentrates in Part II.
Line 14 describes the offer you made for each month. The codes capture whether you offered coverage, to whom (employee only, employee and dependents, employee and spouse, or everyone), and whether it met minimum value. Line 16 is the safe-harbor and relief line. It explains why you shouldn't be penalized for a given month, whether the person wasn't employed, wasn't full-time, was in a waiting period, or your coverage was affordable under a recognized safe harbor.
The two lines work together. A common mistake is reporting a solid offer on Line 14 but leaving Line 16 blank when a safe harbor applies. The offer might be perfect, but without the affordability code, the IRS has no signal that the offer cleared the affordability bar, and the system can flag it. Another frequent slip is a Line 14 and Line 16 combination that contradicts itself, like coding a month as no offer while also claiming an enrollment-based safe harbor.
We won't list every code here because the specific values and affordability percentages shift year to year and your advisor should confirm them. The principle holds: every full-time month needs a Line 14 code that reflects the real offer and, where it applies, a Line 16 code that explains your protection. Blank where something belongs is the enemy.
The codes are only as good as the eligibility tracking behind them. For employees with steady, predictable hours, full-time status is easy to call. The risk lives with variable-hour, seasonal, and part-time staff whose hours bounce around. For those people, employers commonly use a look-back measurement method: you measure hours over a defined period, then lock in full-time-or-not status for a following stability period.
When measurement periods are set up loosely or not at all, two things go wrong. Either someone who averaged full-time hours gets no offer and no 1095-C, which is a missed offer and a penalty exposure, or someone gets reported as full-time when they weren't, which muddies your filing and can create affordability questions you didn't need.
SmartCompliance can run measurement tracking, but it has to be configured to match the periods and method you actually adopted, and the hours data feeding it has to be complete. If hours from a separate time and attendance system aren't flowing in cleanly, your measurement output is built on sand. This is one of the first places we look when a client's ACA numbers feel off.
ACA reporting pulls from across your system: who's full-time, what plans they were offered, what they enrolled in, dependent information if you self-insure, and accurate Social Security numbers and addresses. Each of those is a place for a mismatch to creep in.
Name and SSN mismatches are a quiet, common cause of rejected or flagged forms. So are coverage records that don't line up with payroll deductions, where someone shows as enrolled in benefits but has no corresponding deduction, or the reverse. Before you let forms generate, reconcile the benefits enrollment data against payroll and against your eligibility tracking. The goal is one consistent story per employee across every system.
Run this reconciliation while you still have time to fix the source, not in late January when the clock is running. A clean reconciliation in the fall turns ACA season from a fire drill into a review.
ACA reporting runs on a fixed annual rhythm. Employees generally must receive their 1095-C forms early in the year, and employers must file with the IRS, electronically for most filers, by a later winter deadline. Exact dates shift, and electronic filing thresholds have tightened in recent years, so confirm the current deadlines and filing-method requirements with your advisor or ADP rep rather than relying on last year's calendar.
The mistake isn't usually missing the final deadline outright. It's leaving no room before it. If your first real look at the data is the week forms are due, every error becomes an emergency and corrections pile up. Build your timeline backward from the furnishing deadline with weeks of buffer for reconciliation and review. Late or incorrect returns carry their own penalties, separate from the offer-of-coverage penalties, so the calendar matters as much as the codes.
Even careful employers find errors after filing. A wrong code, a missed employee, an SSN typo. The fix is a corrected return, and the IRS has a defined way to do it. What matters is catching the error and correcting it promptly rather than hoping nobody notices. A timely, good-faith correction is a far better posture than a defended mistake when a penalty notice arrives.
If you do get a notice, generally referred to as a Letter 226-J for proposed employer shared-responsibility penalties, don't ignore it and don't assume it's correct. These letters frequently rest on data the IRS pieced together, and they can be responded to and reduced when your records tell a cleaner story. Read it, gather your documentation, and respond within the window stated in the letter. Confirm your specific response strategy with your tax advisor.
A client came to us in the fall, an employer with a mix of salaried staff and a large pool of variable-hour workers. They'd been generating 1095-C forms in prior years but had never set up a real look-back measurement method, so full-time status for the variable-hour group was being guessed at by whoever ran the file.
We started with reconciliation. Comparing benefits enrollment to payroll deductions surfaced roughly 40 employees whose records didn't line up, some enrolled with no deduction, some the other way. We then set up a measurement period that matched their hiring patterns and pulled in the hours history. That exercise identified about 15 variable-hour employees who had crossed the full-time threshold in the prior year and should have received an offer and a form, and they hadn't.
We didn't invent numbers or paper over the gap. We corrected the current-year reporting, set them up to furnish the missed group properly, and built a fall reconciliation step into their calendar so the same gap couldn't reopen. This is the kind of drift our ADP optimization consultants look for first when a client's numbers feel off. The rough math on avoided exposure ran well into five figures, but the bigger win was that ACA season stopped being a guessing game. Your numbers will differ, and your advisor should confirm the right corrections for your facts.
"We offer coverage to everyone. Do we still have penalty risk?"
Yes. Offering coverage is the foundation, but penalties also turn on whether the offer was affordable, whether it met minimum value, and whether your forms actually prove all of that with the right codes. A generous plan reported with blank or contradictory codes can still draw a notice. The reporting has to match the reality.
"SmartCompliance generates our forms. Doesn't that mean they're right?"
The platform is strong, but it reports what your setup and data feed it. If measurement periods are misconfigured, hours aren't flowing in, or enrollment and payroll don't reconcile, the forms will faithfully report the wrong thing. The tool handles the heavy lifting once the inputs are clean. Getting them clean is the work.
"We got a penalty letter for a year we thought was fine. Now what?"
Don't panic and don't ignore it. These letters often rest on incomplete IRS data and can frequently be reduced or resolved when your records tell the full story. Pull your documentation, respond within the stated window, and confirm your response approach with your tax advisor. We help clients assemble the records side of that response.
A clean ACA year doesn't start in January. It starts months earlier with three habits. First, your measurement method is set up to match how your workforce actually behaves, and hours data flows in completely. Second, you reconcile benefits enrollment against payroll and eligibility every fall, with time to fix the source. Third, you build your filing timeline backward from the furnishing deadline with real buffer, so review replaces panic.
Do those three things and the codes mostly take care of themselves, because the data underneath them is sound. ACA reporting becomes a process you run, not a storm you survive.
We're former ADP service professionals, and we work with ADP exclusively. We've configured SmartCompliance, untangled measurement periods, and helped clients respond to penalty notices. When you call, you get a dedicated consultant who knows ACA reporting cold. No tickets, no hold queues. A real person who picks up.
Worried your 1095-C forms won't hold up? Let's review them before the IRS does. REQUEST A CONSULTATION (ignitehcm.com/solutions/compliance).
ADP and the ADP logo are registered trademarks of ADP, Inc. This content is general guidance only and not tax, legal, or compliance advice. ACA rules, codes, thresholds, and deadlines change; confirm current requirements and your specific obligations with your licensed advisor or ADP representative.