Biweekly vs Semi-Monthly Pay: The Differences, the Paycheck Math, and Which Schedule Fits Your Team

Biweekly and Semi-Monthly Meaning

Biweekly pay means employees are paid every two weeks, always on the same weekday, most often Friday. Each pay period covers exactly 14 days, and there are 26 pay periods in a normal year. Because 26 periods of 14 days is 364 days, one day short of a year, the calendar drifts and every 11 years or so a year contains a 27th payday.

Semi-monthly pay means employees are paid twice a month on fixed dates, typically the 15th and the last day of the month, or the 1st and the 15th. There are always 24 pay periods a year. The periods vary in length, from 13 to 16 days, and the payday falls on a different weekday each time, moving to the preceding business day when it lands on a weekend or holiday.

The confusion between them is partly linguistic. “Bi-weekly” is sometimes misused to mean twice a week, and “bi-monthly” can mean either twice a month or every two months, which is why payroll professionals say “semi-monthly” for twice a month and avoid “bi-monthly” altogether. For the full set of pay period types and how they compare on cost and employee impact, see our guide to what a pay period is. This article focuses on the two schedules most employers are actually choosing between.

The Differences at a Glance

Neither schedule changes annual pay. An employee on $60,000 receives $60,000 either way. What changes is the size and timing of each payment, the complexity of the overtime calculation and the way deductions are spread.

Paycheck Size and Salary Proration

Salaried employees' gross pay per period is the annual salary divided by the number of periods: 26 for biweekly, 24 for semi-monthly. The semi-monthly cheque is therefore larger by 26/24, about 8.3 percent, even though annual pay is identical.

For hourly employees the cheque is simply hours worked in the period multiplied by the rate, so a biweekly cheque for an 80-hour fortnight is the same whichever month it falls in, while a semi-monthly cheque varies with the number of working days in the half-month, from 10 to 12. Hourly staff on semi-monthly pay see uneven cheques, which is one reason hourly workforces are usually paid biweekly. Our guide to how many work hours are in a year gives the 2,080-hour basis behind these conversions.

Proration for new hires and leavers also differs. A biweekly period is always 10 working days, so a mid-period start is a clean fraction. A semi-monthly period might have 10, 11 or 12 working days, and companies must decide whether to prorate on working days or calendar days and apply the rule consistently.

Overtime: Where Semi-Monthly Gets Complicated

The FLSA calculates overtime on a fixed, recurring 168-hour workweek, not on a pay period. Hours over 40 in that workweek are owed at 1.5 times the regular rate, and the employer cannot average two workweeks together. A biweekly pay period contains exactly two full workweeks, so overtime is computed per week and both weeks fall in the same cheque.

A semi-monthly period almost never starts and ends on workweek boundaries. The period from the 1st to the 15th will typically contain one full workweek plus parts of two others. Overtime for a workweek that straddles the 15th cannot be known until the workweek closes, so payroll has to either pay those hours in the following cheque, which the Department of Labor permits as long as payment is made as soon as practicable, or hold the straddling week's hours and reconcile. Many payroll systems handle this automatically, but the hours record must be kept by workweek, not just by pay period, or the calculation cannot be done at all.

This is a recordkeeping requirement as much as a payroll one. For every non-exempt employee the employer must be able to show the hours worked each day and each workweek. A timesheet that only totals the pay period does not satisfy it. Our guide to what overtime is and how it is calculated covers the regular-rate rules, and our exempt vs non-exempt guide covers who is entitled to it.

Benefit Deductions and the Three-Paycheck Months

Health premiums, retirement contributions and most other deductions are quoted monthly. On semi-monthly pay, half the monthly amount comes out of each cheque and the arithmetic closes every month. On biweekly pay the employer has two choices: divide the annual premium by 26 so every cheque carries a slightly smaller deduction, or divide the monthly premium by two and skip the deduction on the third paycheck in the two months that have one.

Those two months are a feature employees notice. Because 26 cheques fall into 12 months, two months each year deliver three paydays rather than two. Personal finance writers treat these as windfalls, though in reality they are the same annual pay distributed unevenly. For employers running the skip-a-deduction method, the three-paycheck months need to be identified in advance each year, because they move.

Garnishments and child support orders are usually expressed per pay period and recalculated when the frequency changes, so a switch between schedules requires notifying the issuing agencies.

2026: A 27-Paycheck Year for Some Biweekly Employers

Because 26 biweekly periods cover 364 days, the extra day each year (two in leap years) eventually pushes a 27th payday into the calendar. Whether 2026 is a 27-paycheck year depends on the payday weekday. January 1, 2026 and December 31, 2026 are both Thursdays, and they are exactly 364 days apart, so an employer that pays biweekly on Thursdays with a payday on January 1 will issue 27 cheques in 2026. Employers paying on any other weekday issue 26.

For hourly staff a 27th cheque is simply another two weeks of hours. For salaried staff the employer must decide how to treat it. The options are to pay the usual 1/26th amount 27 times, which gives employees about 3.8 percent more than their stated annual salary for the year; to divide the annual salary by 27 for that year so cheques are slightly smaller; or to make no change and absorb the cost. Dividing by 27 is legal under federal law but must not take any exempt employee below the salary threshold in any week, and several states require advance written notice of a change in the pay rate. Semi-monthly employers never face this question.

State Pay-Frequency Rules

Most states regulate how often employees must be paid, and the rules can rule out one schedule for part of a workforce. The general pattern:

• Many states require that employees be paid at least semi-monthly, which both biweekly and semi-monthly satisfy. Monthly pay is restricted to certain exempt or executive categories in a number of these states.
• Some states require weekly pay for specific groups. New York requires weekly pay for manual workers unless the employer has an authorisation for less frequent pay, and several New England states require weekly or biweekly pay for hourly employees.
• A few states, including California, set rules about how soon after the period ends wages must be paid, which affects the lag between the close of a pay period and payday.
• States such as Alabama, Florida and South Carolina have no general pay-frequency statute for private employers, leaving the choice to the employer.

Multi-state employers often run both schedules, biweekly for non-exempt staff and semi-monthly for exempt staff, to satisfy the strictest state rule for each group. Check the current statute for each state in which you have employees before changing frequency, and give the notice the state requires.

Which Schedule Should You Choose?

Choose biweekly if most of your workforce is hourly or non-exempt, overtime is common, your time tracking is organised around the workweek, or your state requires frequent pay for hourly workers. The clean alignment between pay periods and workweeks removes the most error-prone part of payroll, and employees on variable hours get predictable, same-weekday paydays.

Choose semi-monthly if your workforce is mostly salaried and exempt, you want deductions and accruals to close monthly for accounting, or you want to avoid the 27-paycheck problem and the three-paycheck months. Finance teams like semi-monthly because 24 periods map onto 12 months with no reconciling items.

Running both is common and perfectly legal, provided each employee is on one schedule and the choice is based on job classification rather than anything discriminatory. The cost is two payroll calendars and two sets of deadlines.

Whatever the schedule, the limiting factor is the hours record. Overtime, proration and the semi-monthly carry-over all depend on knowing when each person started and stopped work each day. E-Monitor's attendance tracking records that automatically and reports hours by workweek and by pay period, and its ADP payroll integration sends the approved period totals straight to payroll. For the people who run this each cycle, see our guide for payroll managers.

Related reading: Pay Transparency and Productivity Data.

Frequently Asked Questions