Biweekly Payroll in 2026: When You Get 27 Pay Periods Instead of 26

Illustrative scenario. The story in this article is a made-up example written to explain the problem. The people, companies and amounts are invented. Dates and week numbers follow the real ISO 8601 and US (Excel System 1) rules.

I was in the middle of reviewing Q1 budget numbers when our accountant, Maria, pinged me on Slack. "Hey — quick question. Does our payroll calendar account for the 53-week year in 2026?"

I stared at the message. 53-week year? I had never heard those words together before. I'd been running this startup's finance operations for two years and I couldn't tell you whether a year could have 53 weeks. I assumed 52 was a fixed number — like 12 months, 365 days. Fixed.

I was wrong. And that wrongness was about to cost us.

Biweekly means 26 paychecks. Except when it doesn't.

Here's the math I had in my head when I set up our payroll calendar in 2024:

52 weeks per year. Biweekly pay = every 2 weeks. 52 divided by 2 = 26 pay periods. Each employee gets 26 paychecks. Annual salary divided by 26 = per-paycheck amount. Simple.

I built our entire payroll schedule on that assumption. Two pay periods per month, with a couple of "three paycheck months" sprinkled in. The spreadsheet was clean, the formulas worked, and nobody complained for two years.

Then Maria sent me a Wikipedia link to ISO week date. I scrolled down to the section about "Weeks per year" and saw this line:

A year has 53 weeks if and only if it starts or ends with a Thursday (in the Gregorian calendar).

I opened my calendar. January 1, 2026 is a Thursday. My stomach dropped.

The $18,460 I didn't budget for

Let me explain why this matters with real numbers. Say you have an employee making $60,000 a year on biweekly pay. Most years, you calculate their per-paycheck amount as $60,000 / 26 = $2,307.69. Twenty-six checks, $60K total.

2026 has 53 Thursdays: it starts and ends on a Thursday. A biweekly schedule with Thursday paydays that starts on January 1, 2026 therefore has 27 paydays, not 26. If your payroll calendar just generates a check every two weeks, you're going to issue that 27th check, which means paying that employee $62,307.69 instead of $60,000. (Other schedules hit 27 paydays in other years: it happens when one of your paydays falls on January 1, or on January 1 or 2 in a leap year.)

For one employee, that's an extra $2,307.69. For our team of eight people on that salary, it's about $18,460 in unplanned payroll expense. That's a real chunk of runway for a startup.

But here's the thing I didn't realize until I dug deeper: the problem isn't always an extra check. For hourly staff, the question is whether your budget counts weeks or days. If the budget assumes 52 weeks × 40 hours = 2,080 hours per person, but payroll runs by week and 2026 has a 53rd payroll week, that week adds another 40 hours per person.

Why payroll software doesn't always catch this

You'd think payroll software would handle this automatically. Many tools can handle a 27th pay period, but how they do it, and whether they warn you, depends on the product and on how your pay schedule is set up. A lot of small businesses also run payroll from a spreadsheet or a lightweight tool with default settings.

The extra pay period simply shows up in the calendar, and if you're not paying attention, which I wasn't, you don't notice until the money is already out the door. Check your provider's documentation for how it treats a 27th period.

I spent an afternoon reviewing our payroll setup and found three different places where the 53-week assumption was missing:

• Our annual compensation budget spreadsheet divided everything by 26 — hardcoded
• Our cash flow projection assumed exactly 26 pay periods per fiscal year
• Our contractor agreements specified "26 biweekly payments" instead of "biweekly payments for the duration of the contract"

That third one was the one that actually worried me. We had written a contract with a contractor that explicitly said 26 payments. If they worked through the end of 2026, they were entitled to 27. The contract language was technically wrong, and while I doubted they'd sue us over one extra payment, it was a legal loose end I didn't want dangling.

Which years have 53 weeks?

After my panic-induced research session, I made myself a cheat sheet. A year has 53 ISO weeks when:

• The year starts on a Thursday (like 2026)
• Or the year is a leap year that starts on a Wednesday (like 2020 was)

This happens roughly every 5 to 6 years. Recent 53-week years: 2009, 2015, 2020, 2026. Next ones: 2032, 2037, 2043.

You can also just check weeknumber.cc and look at the full year calendar. If December 31 falls in Week 53, you have a 53-week year. It takes about 3 seconds to check.

I now do that check every October during budget season. It's the first thing I do, before I open any spreadsheet.

What you should do right now (like, today)

If you handle payroll or budgeting for a company — even a tiny one — here's what I'd suggest:

First, check if your payroll calendar has 26 or 27 pay periods for 2026. Don't assume. Open the actual calendar and count.

Second, if you have 27, decide how you're handling it. Options include: adjusting the per-paycheck amount so the annual total stays the same (for salaried employees), budgeting the extra period as a separate line item, or — and I learned this is a thing some companies do — skipping the last pay period and rolling it into the first one of the next year. That last one is messy and I don't recommend it, but it exists.

Third, talk to your accountant or whoever handles your financial projections. Make sure the extra pay period is reflected in cash flow forecasts. A surprise $18,460 in payroll is a lot easier to handle when you know it's coming six months in advance.

I caught our 53-week problem in March of 2026, which gave us most of the year to adjust. If I'd caught it in November, I would have had about 6 weeks to scramble. The earlier you check, the less painful it is.

Maria still jokes about it. "Remember when you didn't know years could have 53 weeks?" Yes, Maria. I remember every time I update the payroll calendar.