How PTO Accrual Works: Monthly Accrual, Proration, Caps, and Tenure Tiers Explained

Accrual vs Frontloading: Two Ways to Grant PTO

There are two common ways employers grant paid time off. Accrual (also called incremental accrual) awards a fraction of the annual allowance on a recurring schedule, most often monthly or per pay period, so an employee's available balance grows gradually as they work. Frontloading (also called lump-sum) grants the full annual allowance on day one of the year or on the employee's hire anniversary, with nothing accrued gradually afterward.

Accrual is more common for hourly and non-exempt employees because it ties leave to time actually worked and naturally handles employees who leave mid-year, since they've only earned a partial balance. Frontloading is simpler to administer and is common for salaried employees or companies that want every employee's balance to reset identically at the start of the year. Some employers frontload the current year's allowance but still track it against an accrual-equivalent rate for payout-at-termination purposes, since several states require paying out only what has been earned, not what was frontloaded.

A monthly accrual rate is calculated by dividing the annual allowance by 12. An annual allowance of 15 days becomes 1.25 days per month; 10 days becomes 0.833 days per month; 20 days becomes 1.667 days per month. If accrual runs per pay period instead of per month, divide the annual allowance by the number of pay periods (26 for biweekly, 24 for semimonthly) instead of by 12.

Worked Example: Monthly Accrual From a Mid-Month Hire Date

Take a policy of 1.25 days per month (15 days/year), a 15-day annual cap, and 5 days of carryover. An employee is hired on March 15. Most accrual engines count only whole completed months of employment, so this employee's first partial month (March 15-31) typically does not generate accrual; the clock starts at the next full month.

By June 30, this employee has completed 3 full months of employment (April, May, June): 3 × 1.25 = 3.75 days accrued. If your policy instead counts the hire month itself as month one regardless of the exact hire day (a simpler, more generous rule some employers choose for administrative ease), the same employee would show 4 months × 1.25 = 5 days accrued by June 30 - which is the number used in this guide's title example because it's the more common simplified approach in small-business policies. Either method is defensible; the point is that the policy document has to say explicitly which one applies, because the two produce different numbers for the exact same hire date.

The formula in either case is: accrued days = MIN(annual cap, completed months of service since hire × monthly accrual rate) + capped carryover from the prior year. The MIN() function matters - without it, accrual would keep growing past the annual cap for any employee who doesn't use their PTO.

How Caps Stop Accrual, and What Happens When an Employee Hits One

An accrual cap (sometimes called a use-it-or-lose-it ceiling in employer-side terminology, though that phrase more precisely refers to year-end forfeiture, covered in a separate guide) is the maximum balance an employee can hold at any point in time. Once an employee's accrued-plus-carryover balance reaches the cap, most policies stop further accrual until the balance drops below the cap again, either from the employee taking time off or from a payout.

Using the 1.25/month, 15-day cap example: an employee who never takes PTO reaches the 15-day cap after 12 months and simply stops accruing more until they use some. An employee who takes 3 days off when they're at the 15-day cap immediately resumes accruing at 1.25/month from the new 12-day balance. This is different from a use-it-or-lose-it policy, which forfeits days at a fixed calendar date (typically year-end) rather than pausing accrual at a rolling cap - see our guide on use-it-or-lose-it PTO for that distinction and the states where forfeiture is restricted.

Tenure Tiers: Accrual Rates That Increase With Seniority

Many PTO policies increase the accrual rate at set tenure milestones to reward longer employment, commonly at the 2-year and 5-year marks. A representative tier structure: base rate 1.25 days/month (15 days/year) from hire, stepping up to 1.50 days/month at 2 years of service (base +0.25, 18 days/year) and to 1.75 days/month at 5 years (base +0.50, 21 days/year). Note that in this structure the 5-year tier replaces the 2-year tier rather than stacking on top of it - the bonus is always applied to the base rate.

The tier change applies from the employee's service anniversary forward, not retroactively - an employee who crosses their 2-year anniversary in June accrues at the old rate through May and the new rate starting June. A tracker or spreadsheet needs to reference the employee's hire date against the current date at each accrual run to apply the correct tier automatically; doing this by hand across a growing team is where manual trackers most commonly drift out of sync with actual policy.

Carryover: What Moves Into the New Year

Carryover is the portion of an unused balance that rolls from one year into the next, subject to its own cap - which is often lower than the accrual cap. In the running example, a 5-day carryover cap means an employee ending the year with 8 accrued-but-unused days carries over only 5; the remaining 3 are either forfeited (if legally allowed in that state and disclosed in the policy) or paid out, depending on the employer's written policy and applicable state law. See our dedicated guide on PTO carryover rules for worked examples of the year-end calculation, and how to calculate PTO payout for the payout-at-termination formula and a state-by-state summary of payout requirements.

Running These Numbers Without a Manual Spreadsheet

The formulas above - proration by completed months, MIN() against an annual cap, tier-based rate changes at service anniversaries, and capped carryover - are exactly what a manual spreadsheet has to replicate correctly for every employee, every accrual cycle, and they're also exactly where hand-built trackers most often break: a hire-date formula that doesn't update, a tier that isn't applied on the right month, a cap that isn't enforced.

Our free PTO accrual calculator (tabletemplates.com/free/pto-accrual-calculator-excel/) runs this exact math - monthly rate times months worked, capped at your annual maximum, plus carryover - so you can check a balance without building the formulas yourself. You enter the months worked and the tier-adjusted rate for each employee; hire-date proration and automatic tenure tiers are what our paid PTO tracker computes for you.