What it means
Most retirement plans reward length of service: the longer you stay, the more of the employer's contributions you own outright. A break in service is the formal way a plan measures a gap in that service, and it is normally defined in hours rather than dates.
The common test is a plan year in which the employee is credited with 500 or fewer hours of service. The concept matters because it decides two separate things: whether a returning employee has to wait again to join the plan, and whether their old vesting credit survives.
A worker who was 60% vested before leaving usually wants those years back rather than starting from zero. Employers care too, because restoring credit changes the size of the liability sitting on the balance sheet.
The main protective rule is the rule of parity. Pre-break service can be permanently disregarded only if the number of consecutive one-year breaks is at least five, or greater than the years of service earned before the break, whichever is larger.
In practice that means short absences almost never destroy vesting credit for someone who was already several years in. Breaks in service also appear outside pensions.
Employers use similar tests for health plan eligibility after a rehire, for holiday and severance calculations, and for the waiting period before someone rejoins a share scheme. The definitions differ from plan to plan, which is why the plan document, not general practice, is the thing to read.
One nuance catches people out: maternity, paternity and certain protected leaves usually generate credited hours specifically to prevent a break. Military service and approved sabbaticals often get similar treatment.
A gap that looks like a break on a payroll report may therefore not be one under the plan rules.
In practice
Real-world examples.
Example
A regional hospital rehires a theatre nurse who left three years earlier after four years of service. Because her three consecutive break years are fewer than the five-year threshold and fewer than the greater of five and her four prior years, the plan restores her earlier vesting credit and she rejoins at 4 x 20% = 80% vested rather than zero.
Example
A software firm keeps a departing engineer on a part-time consultancy arrangement of about eight hours a week, roughly 400 hours across the plan year. Because 400 is below the 500-hour threshold, the year still counts as a break in service despite the continuing relationship. The finance team had assumed the arrangement preserved his benefit credit and had to correct the vesting schedule.
Example
A food manufacturer runs a seasonal packing line where staff work 900 hours across the harvest and nothing for the rest of the year. Because 900 exceeds 500, no break in service arises and the workers keep accruing eligibility year after year. The plan's designers chose the 500-hour test deliberately so that seasonal crews were not quietly excluded.
Formula
Calculation
Formula: a one-year break in service occurs in any plan year in which an employee is credited with 500 or fewer hours of service. Vested percentage = years of vesting service x the plan's vesting rate per year.
Worked example: Priya joins a company on 1 January 2019 and works full time through 2019, 2020 and 2021, earning well over 1,000 hours in each of those three plan years. The plan vests employer contributions at 20% per year of service, so she is 20% x 3 = 60% vested. Her employer contribution account holds $18,000, of which $18,000 x 60% = $10,800 is hers to keep.
She resigns in January 2022 with only 320 hours credited that year, so 2022 counts as a one-year break in service, as do 2023 and 2024. That is three consecutive break years. The rule of parity would erase her earlier credit only if the consecutive breaks reached five, or exceeded her three prior years of service, whichever is greater; five is the greater figure, so her three years survive.
She returns in 2025 and works full years in 2025 and 2026, reaching 3 + 2 = 5 years of vesting service. At 20% per year that makes her 5 x 20% = 100% vested, so the whole employer account is hers.Case study
Seen in the real world.
Northbourne Cabinetry is an illustrative, fictional joinery business with 220 staff and a retirement plan that vests employer contributions at 20% a year. During a downturn it laid off 40 workers in March, most of whom had between two and six years of service and had been credited with fewer than 500 hours for that plan year.
Eighteen months later demand recovered and Northbourne rehired 26 of them. The payroll team initially set every returning employee back to zero vesting, on the assumption that leaving reset the clock. A benefits adviser pointed out that only one full break year had elapsed for most of them, far short of the five-year parity threshold, so their prior service had to be restored.
Correcting the records moved one worker with five prior years from 0% to 5 x 20% = 100% vested, releasing $31,000 that the plan had been about to forfeit. Northbourne now runs a break in service check as a standard step in its rehire process, which costs the payroll team about an hour per rehire and has prevented several similar errors.
Watch out
Common mistakes.
- Assuming any gap in employment automatically wipes out vesting credit, when the rule of parity protects most returning employees.
- Measuring a break in service by calendar dates rather than by credited hours in a plan year.
- Treating protected leave such as maternity or military service as a break, when plans normally credit hours specifically to prevent one.
Questions
People also ask.
Does a break in service affect eligibility to join the plan as well as vesting?
Yes, a returning employee may face a fresh waiting period under some plan designs, although many plans readmit rehires immediately.
What counts as an hour of service?
Generally any hour for which the employee is paid or entitled to payment, including holiday, sickness and certain paid leave, not only hours actually worked.
Can an employer choose a stricter break in service rule than the 500-hour test?
No, plans may be more generous to employees but cannot strip credit faster than the minimum standards allow.
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