Whether PTO accrues while you’re on leave depends on the kind of leave, whether you’re being paid during it, and what your employer’s written policy does for people on comparable absences. Federal law does not require accrual to continue during unpaid FMLA leave, but it also does not forbid it, and many employers keep the clock running for at least part of an absence. The real answer usually lives in your handbook, your collective bargaining agreement, or your state’s paid leave statute rather than in the federal rules themselves.
The FMLA Default
Under 29 CFR 825.215, an employee “may, but is not entitled to, accrue any additional benefits or seniority during unpaid FMLA leave.”1eCFR. 29 CFR 825.215 – Equivalent Position The companion regulation, 29 CFR 825.209(h), ties the benefit question to what the employer already does for other kinds of absence: your entitlement to benefits other than group health insurance during FMLA leave “is to be determined by the employer’s established policy for providing such benefits when the employee is on other forms of leave (paid or unpaid, as appropriate).”2eCFR. 29 CFR 825.209 – Maintenance of Employee Benefits
That is the actual protection. An employer can freeze PTO accrual during unpaid leave across the board, and that is lawful. What it cannot do is single out FMLA leave for worse treatment than other unpaid absences. The comparison has to be apples to apples: unpaid FMLA leave gets measured against other unpaid leaves like personal leave or sabbaticals, not against paid time off.
Paid Leave Substitution Changes the Picture
Most employees discover this the hard way. Under 29 CFR 825.207, an employer “may require the employee to substitute accrued paid leave for unpaid FMLA leave.”3eCFR. 29 CFR 825.207 – Substitution of Paid Leave Substitution means your paid leave runs at the same time as your FMLA leave: your PTO bank drains, you keep getting a paycheck, and your 12-week FMLA clock ticks either way. You can also elect substitution voluntarily.
For accrual, this matters because most payroll systems earn PTO on paid hours. While you are drawing down your existing PTO, you are typically also earning a smaller amount of new PTO on the paid time you take. Once the paid bank runs out and you shift into fully unpaid status, that accrual usually stops.
One catch: if you do not follow your employer’s normal procedures for requesting paid leave, the employer can deny substitution. You still get the unpaid FMLA protection, but you lose the paycheck and the accrual that goes with paid status. If neither side elects substitution, your PTO bank stays untouched and waiting for you when you return.3eCFR. 29 CFR 825.207 – Substitution of Paid Leave
What Your Handbook Actually Controls
For most employees, the employee handbook decides more than the federal regulation does. Two provisions deserve a careful read before leave starts.
Accrual Triggers
Policies often condition accrual on specific facts: a minimum number of hours per pay period, active employment on the last day of the month, or simply being in paid status on the payroll. If your handbook only credits PTO in pay periods where you work at least 60 hours, an unpaid leave spanning several pay periods will freeze the balance. Some employers accrue based on length of service regardless of hours worked, which means the balance keeps growing even during unpaid time. Read the definitions of “active employment” and “qualifying hours” in your policy before you go out.
Caps and the Leave Trap
Many employers cap PTO. Once you hit the maximum, accrual pauses until you use some of the balance down. If you start unpaid leave already close to the cap, you cannot burn PTO to make room, and weeks of potential accrual can simply never materialize. Some states restrict use-it-or-lose-it policies or ban forfeiture of earned vacation, but those rules do not necessarily stop a cap from freezing new accrual. Checking your balance against the cap ahead of time gives you a chance to address it with HR or use time before you leave.
Military Leave Gets Stronger Treatment
Military leave under USERRA is the strongest case for continued accrual. 38 U.S.C. ยง 4316 entitles a returning service member to the seniority and seniority-based benefits they would have earned if they had not been away.4Office of the Law Revision Counsel. 38 USC 4316 – Rights, Benefits, and Obligations of Persons Absent From Employment for Service in a Uniformed Service If vacation accrues at a higher rate as tenure increases, a service member who returns after two years of duty has to be credited with those two years for accrual-rate purposes.
For benefits that are not tied to seniority, USERRA uses the same equal-treatment logic as FMLA: the service member gets what the employer provides to employees on comparable leaves. There is one meaningful advantage over FMLA. Your employer cannot force you to burn accrued vacation during military service; you can choose to use it, but the choice is yours.4Office of the Law Revision Counsel. 38 USC 4316 – Rights, Benefits, and Obligations of Persons Absent From Employment for Service in a Uniformed Service
ADA Leave as a Reasonable Accommodation
Leave taken as a reasonable accommodation under the ADA follows the same equal-treatment pattern. The EEOC’s guidance states that an employer “must continue an employee’s health insurance benefits during his/her leave period only if it does so for other employees in a similar leave status,” and the same logic reaches other benefits like PTO.5U.S. Equal Employment Opportunity Commission. Enforcement Guidance on Reasonable Accommodation and Undue Hardship Under the ADA If your employer freezes accrual for all unpaid leaves, it can freeze yours. If it continues accrual for other unpaid leaves, it must continue yours.
ADA leave has no built-in 12-week cap, so if you need a longer accommodation and the employer agrees, the equal-treatment rule applies for the whole duration. Employees on a reduced schedule as an accommodation are treated consistently with other part-time employees, which may mean a proportionally lower accrual rate.
State Paid Family and Medical Leave
Thirteen states and the District of Columbia have enacted paid family and medical leave programs as of 2026.6National Conference of State Legislatures. State Family and Medical Leave Laws These programs pay a share of your wages through a state-run insurance fund while you’re out for qualifying reasons like a new child or a serious health condition.
Whether PTO accrues while you’re drawing state benefits varies. Because the wage replacement comes from the state rather than from hours worked for your employer, company accrual policies often treat you as being on unpaid leave for internal purposes even though a check is coming in. State law may guarantee your job and benefits on return, but restoration is not the same as continued accrual during the absence. Delaware’s program, which launched in 2026, took the additional step of prohibiting employers from forcing workers to exhaust accrued PTO before accessing state benefits, though both sides can still agree to use PTO as a top-up.
Separately, roughly 19 states and the District of Columbia mandate paid sick leave, generally accrued at a rate tied to hours worked. If you’re on unpaid leave and logging no hours, there is nothing for the state accrual formula to key off, so new sick time does not build up under those statutes. That’s different from PTO earned on length of service.
Workers’ Compensation Leave
Workers’ comp leave is its own category, governed largely by state law and by the terms of your employment. No federal statute mandates PTO accrual during a workers’ comp absence the way USERRA mandates seniority credit for military service. Many employers treat it like any other unpaid leave for accrual purposes, which freezes the balance. If your handbook or employment agreement specifically promises accrual during injury-related absences, the employer is bound by that promise. Union contracts frequently address the point directly. Check the specific documents rather than assume.
Union Contracts
A collective bargaining agreement usually treats accrual during leave differently from a standard handbook. Union contracts often tie vacation to seniority tiers, and whether the tiers keep advancing during a leave depends on how the contract defines qualifying service. Some agreements explicitly count approved leaves toward seniority for accrual; others pause the clock.
A CBA is a binding contract, and where it conflicts with a company policy on leave benefits, the CBA controls. Before leave, ask your steward what the agreement guarantees. The answer for a union employee can be substantially different from the answer for a non-union coworker at the same employer.
What You Keep When You Return
Even when accrual pauses, the balance you already earned is protected. Under FMLA, any benefits you had accrued before leave began must be available when you return, and your employer cannot zero out the PTO bank or treat it as forfeited because you were away.1eCFR. 29 CFR 825.215 – Equivalent Position The one exception is PTO that was substituted for unpaid leave under 29 CFR 825.207, which you already used and got paid for.
Benefits also resume at the same level, adjusted for any changes that applied to the whole workforce while you were out. If everyone’s accrual rate went up during your absence, yours does too.
Before Your Leave Starts
The worst day to find out your PTO stopped growing is your first day back. A few checks in advance make a real difference:
- Read the accrual section of your handbook, and specifically how “active employment” and “qualifying pay period” are defined.
- Compare your current balance to any cap. If you are near the ceiling and heading into unpaid time, you may lose accrual you can never recover.
- Ask HR whether paid-leave substitution is mandatory during FMLA leave. If it is, expect a smaller bank on return but continued accrual for the paid portion.
- Get the answer in writing. A confirmation email about how accrual will be treated during your leave is far easier to enforce than a verbal assurance.
- If you are unionized, check the CBA with your steward. It may guarantee accrual protections the handbook does not.
Federal law sets a floor. Employer policies, state statutes, and union contracts sit on top of it, and the gap between returning to a full PTO bank and returning to a frozen one is usually decided by a few paragraphs in your handbook or contract that are worth reading before you sign the leave paperwork.