# Small group age rating calculator

Source: https://www.getprescience.com/tools/small-group-age-rating-calculator
Author: Rishab Jain, Cofounder and CEO, Prescience
Published: 2026-11-12
Updated: 2026-11-12
Cite as: Rishab Jain. "Small group age rating calculator." Prescience, November 12, 2026. https://www.getprescience.com/tools/small-group-age-rating-calculator

In the ACA small group market a plan has one base rate, and every person's premium is that rate times their age factor. Paste the ages from a census and the plan's age-21 rate to see the group's monthly premium, the spread from youngest to oldest, and the composite rate that would bill the same total.

- **Age 21 factor:** 1.000
- **Age 64 and over:** 3.000 (the 3:1 limit)
- **Age 14 and under:** 0.765
- **Rating factors allowed:** Age, area, tobacco, family size

## Rate the census

_Interactive calculator: open the page in a browser to use it. The rules and figures it applies follow._

Paste the age column from a census, or type the ages separated by commas, and enter the plan's monthly rate for a 21-year-old in the group's rating area. The default is a 10-person census from 24 to 61 at a $420 age-21 rate. The calculator rates employees only; add each covered spouse and child as their own line if you want the full bill.

Ages stay in the browser, and the tool never sees names or dates of birth. A list of ages is enough.

## How ACA age rating works

The ACA limits small group premiums to four factors: age, geographic rating area, tobacco use and family size. The carrier files one base rate per plan and rating area, and each person's premium is that base rate times their age factor. Health status, gender and the group's claims can't change the rate.

The federal default age curve sets a 21-year-old at 1.000 and a person 64 or older at 3.000, which is the 3:1 limit the ACA puts on age rating. Children 14 and under share one factor of 0.765, and the curve rises each year from 15 to 64. A handful of states, including Massachusetts, Minnesota, Oregon and Utah, plus DC, use their own curves, and New York and Vermont don't allow age rating at all. This calculator uses the federal default.

**Selected factors on the federal default curve**

| Age | Factor | At a $420 age-21 rate |
| --- | --- | --- |
| 14 and under | 0.765 | $321.30 |
| 21 to 24 | 1.000 | $420.00 |
| 30 | 1.135 | $476.70 |
| 40 | 1.278 | $536.76 |
| 50 | 1.786 | $750.12 |
| 60 | 2.714 | $1,139.88 |
| 64 and over | 3.000 | $1,260.00 |

Family premiums are built the same way, person by person. Only the three oldest children under 21 are rated, so a family with five young children pays for three.

## A worked census

**Ten employees from 24 to 61**

Illustrative numbers. A 10-person group's employees are 24, 27, 29, 31, 34, 38, 41, 45, 52 and 61. The plan's age-21 rate in their rating area is $420 a month.

- Age 24: $420 × 1.000: $420.00
- Age 41: $420 × 1.302: $546.84
- Age 52: $420 × 1.952: $819.84
- Age 61: $420 × 2.810: $1,180.20
- All ten employees, monthly: $6,003.48
- Composite rate: $6,003.48 ÷ 10: $600.35

The group pays $6,003.48 a month, $72,041.76 a year, for employee coverage. The 61-year-old's premium is 2.81 times the 24-year-old's. If the 61-year-old retires and a 25-year-old is hired, the total falls to $5,244.96 and the composite to $524.50, a 12.6% drop with no change in the plan.

That last line is the reason a small group's renewal can move sharply in either direction with no change in the carrier's rates. The census changed. Rerun the census at every renewal before you blame the carrier.

## List billing and composite rates

By default, small group plans are list billed: the carrier bills each person's age-rated premium. Where the state allows it, a carrier can offer composite rates instead, one average rate per tier that bills the same total for the plan year. The federal rule requires the composite to be derived from the per-member rates, and it stays fixed for the plan year even if the census changes.

- **List billing** is exact. Each new hire's premium is their own, so the bill tracks the census every month.
- **Composite rates** are simpler to explain and to set contributions on, because every employee-only enrollee has the same premium. A percentage contribution on a composite treats a 25-year-old and a 60-year-old the same.
- **With list billing and a percentage contribution**, older employees pay more in dollars for the same plan. Many employers set a flat contribution based on the composite or the average to avoid that.

> **Use the composite for contributions:** Even when the carrier list bills, you can set the employee's contribution from the composite. The employer then carries the age spread, and every employee sees the same price for the same plan.

## Using the census in a quote

The age-21 rate is the single number that changes between carriers and plans; the age curve is the same for every fully insured small group plan in the state. To compare two plans for one census, run each plan's age-21 rate through the same list of ages. The ratio between their totals equals the ratio between their base rates, so the cheaper base rate is cheaper for every census.

That is not true of level-funded and self-funded plans, which are priced on the group's expected claims and are not bound to the ACA's rating factors. A young, healthy group may see a much lower level-funded quote than its age-rated premium; an older group may see the reverse. Our guide to [level-funded, self-funded and fully insured plans](https://www.getprescience.com/guides/level-funded-vs-self-funded-vs-fully-insured) covers the trade-off.

Ask the client for ages as of the plan's effective date. Carriers rate on the age at the start of the plan year, so a census taken in March for a January renewal can put someone in the wrong year.

> **Prescience Diamond: A company health plan with an effective $0 deductible.** A fixed quote on the same census lets you put a single number next to the age-rated total.
> - **An effective $0 deductible** and simple copays shown before a visit
> - **A broad national PPO network,** plus providers we contract with directly
> - **24/7 physician-led care navigation** that books visits and explains costs
> - **Usually 10–20% below comparable fully insured coverage,** fixed in your quote, with no admin fees
> Best for teams of about 15 or more that want one great group plan. [Get a Diamond quote](https://www.getprescience.com/get-started?p=Employer&product=diamond)

**Apply the age-rating illustration to a real client census**

Use checked birth dates, home ZIP codes and family tiers in the quoting process. Keep the illustration separate from the carrier's actual product, geography and written rates.

[Create a broker account](https://www.getprescience.com/brokers/apply)

## Getting the census right for age rating

Age-rated premiums are only as accurate as the ages on the census. A few checks catch most errors before a carrier does:

- **Use dates of birth, not ages.** Ages go stale; a date of birth lets you compute the age at the effective date.
- **Remove terminated employees and add confirmed new hires.** The census should describe who will be enrolled on day one.
- **Check outliers.** An age of 4 or 104 on an employee line is a typo, and the calculator drops ages outside 0 to 120 for that reason.
- **Separate enrolling and waiving employees.** Only people who enroll are rated; a census of everyone eligible overstates the premium.

Count dependents carefully. A spouse is rated at their own age, and each child is rated at theirs, up to the three oldest under 21. A census that lists only employees will understate a family-heavy group's premium by a wide margin; one that lists every child in a large family will overstate it.

Finally, rerun the census when the effective date moves. A group quoted for March that slips to May may have employees cross into a new age band, and the difference between 63 and 64 is the difference between a factor of 2.952 and 3.000. The carrier's final rates will use the census as of the date coverage starts.

Our guide to [reading a census file](https://www.getprescience.com/for-brokers/how-to-read-a-census-file) covers the rest of the fields that move a quote.

## What this calculator does not include

It does not apply a tobacco surcharge, a state-specific age curve or the rating-area differences inside a multi-state group. It rates employees only unless you add dependents as separate ages. And it uses one base rate, so it can't show the difference between plans unless you run each plan's rate separately.

It also does not apply to individual-market ICHRA plans, which use the same age curve but a different base rate in each employee's own rating area. Our [ICHRA age rating calculator](https://www.getprescience.com/tools/ichra-age-rating-calculator) handles allowances that vary by age.

## Frequently asked questions

**How are small group health insurance premiums calculated?**

The carrier sets a base rate for each plan and rating area. Each person's premium is the base rate times their age factor, adjusted for tobacco where the state allows it. The group's premium is the sum for everyone enrolled.

**What is the 3:1 age rating limit?**

The ACA allows the oldest adult's premium to be at most three times a 21-year-old's for the same plan. On the federal default curve, age 64 and older has a factor of 3.000.

**What is a composite rate?**

One average premium per tier that bills the same total as rating each person by age. Where states allow it, the composite stays fixed for the plan year.

**Why did our renewal go up when the carrier's rates barely changed?**

Usually because the census aged. Each employee is a year older at renewal, and a change in who is enrolled can move the total by much more than the carrier's rate change.

**Do children count toward the premium?**

Yes, each covered child is rated by age, but only the three oldest children under 21 in a family are charged.

**Do all states use the federal age curve?**

No. A few states and DC publish their own curves, and New York and Vermont don't allow age rating.

## Sources

- [45 CFR 147.102, Fair health insurance premiums](https://www.ecfr.gov/current/title-45/subtitle-A/subchapter-B/part-147/section-147.102)
- [CMS, Market rating reforms](https://www.cms.gov/marketplace/private-health-insurance/market-rating-reforms)
- [CMS, State-specific age curve variations (federal default age curve)](https://www.cms.gov/files/document/statespecagecrv042517pdf)
- [HealthCare.gov, How insurance companies set health premiums](https://www.healthcare.gov/how-plans-set-your-premiums/)