The Unit Stat Calendar and Your Workers' Comp EMR

Updated September 15, 2026

You got the stale reserve corrected three months ago. You checked your mod last week. Nothing moved. You start to wonder whether the correction actually happened, or whether anyone even followed through on it. It happened. It just isn’t on your calendar yet. It’s on the bureau’s.

Your mod runs on a filing schedule, not your calendar

Your workers’ comp EMR (experience modification rate) doesn’t update the moment something changes. A new one is calculated once a year, taking effect at your rating effective date, using data as of a specific valuation date that’s already passed by the time you see the new number. The data behind all of it comes from your carrier’s unit statistical report, the filing that reports your payroll and claims to the rating bureau for a given policy period. That filing, not the day you fixed something, is what sets the clock for the next rating.

This is the single most common source of frustration in this whole process. A contractor gets a reserve lowered or a stale claim closed, and expects to see the mod respond. It doesn’t respond right away. A reserve that drops, or a claim that closes for less, after the valuation date isn’t an error in the data your carrier reported. That change shows up on the next unit stat report and the ratings built from it, and the next rating might be a year away.

Which fixes change your current mod and which wait for the next one

A reporting error works differently. If your carrier reported the wrong payroll, put payroll under the wrong class code, or reported a claim that isn’t yours or the same claim twice, the carrier files a correction with the bureau. In NCCI states, that correction produces a revised mod. So the rating sitting in front of a GC right now can change when the error behind it is fixed. In NCCI states, ownership or combination changes can also revise the current mod and up to two before it.

A reserve that comes down, or a claim that closes for less, after the valuation date is the other kind of fix. It reaches the next rating, and the one after that, since the same claim can sit in up to three consecutive ratings depending on when in the three-year window it falls.

Either way, start as early as you can. Your agent or carrier can tell you when a revised mod is expected, and a reserve change has to be in the carrier’s file by the valuation date of the next report to show up there.

The three points in your year worth watching

Right after your rating effective date. This is the point furthest from your next rating calculation, which means it’s the point where a correction has the most runway to matter. If you’re going to chase down a stale reserve, doing it here instead of waiting gives it the best chance of reaching the next rating instead of the one after that. If you find a reporting error, like a misclassified payroll figure, raising it here means a revised mod is in place for more of your year.

A few months before your policy renewal. Unit stat filings happen on the carrier’s schedule, and the exact timing varies by carrier and by state, but the valuation date for your next rating usually comes months before your renewal, so a reserve change you raise this close to renewal has likely already missed it. If you know a reserve is stale and you haven’t raised it yet, raise it now so it’s in the carrier’s file before the valuation date after that, rather than letting it slip another year.

Before a bid or a bonding renewal you know is coming. If a specific deadline is approaching, your goal shifts from fixing the rating itself, which you likely can’t do in time, to having documentation ready: a verified worksheet, a letter from your agent, and a clear account of what’s being corrected and when it will show up.

What this means for how you check your own numbers

Because a new mod comes out once a year, checking your worksheet against your loss runs and payroll once, right after a rating comes out, gives you the most useful information: what’s wrong, which fixes can revise the mod you have now, and how much runway a stale reserve has before the next valuation date. Checking again the week before a bid is due tells you the same things, just with almost no time left to act on them.

If you’ve never checked your worksheet against your actual records, there’s no wrong time to start, since a reporting error you find can still be corrected, and a stale reserve can still reach a future rating. But the earlier in your policy year you do it, the more of that chance you actually get.

Your renewal date isn’t always your rating effective date

Most contractors assume the two are the same, and often they are, since a new mod typically takes effect alongside a new policy period. But a mid-term policy change, a carrier switch, or an unusual renewal cycle can put a little daylight between the date your policy renews and the date a new rating actually takes effect. If the two dates don’t line up for your policy, it’s the rating effective date that sets the clock on your next rating, not the renewal date on your calendar, so it’s worth confirming which one you’re actually watching.

Asking your agent about your own timeline

Your rating effective date and the general shape of your carrier’s filing schedule are things your agent or carrier can confirm specifically for your policy, and it’s worth asking rather than assuming a generic timeline applies to you. Knowing your own dates is what turns “eventually” into an actual plan: when to raise a correction, when your agent expects a revised mod, and how much time a stale reserve has before the next valuation date.

Checking your numbers on your own schedule

The free EMR Cost & Bid Check calculator shows what your current mod is costing you against common thresholds any time of year. A full verification compares your worksheet against your actual loss runs and payroll, line by line, and tells you exactly what to send your agent or carrier, and whether each fix should revise your current mod or wait for the next one. It’s a flat fee, no contingency, and the savings are yours. Get on the waitlist to be first in line.