The 941 lookback period is the fixed 12-month window the IRS uses to decide whether you deposit federal payroll taxes monthly or semiweekly during the current calendar year. For 2026, that window runs from July 1, 2024 through June 30, 2025. Add up the tax liability you reported on line 12 of each Form 941 filed during those four quarters. If the total is $50,000 or less, you’re a monthly depositor for all of 2026. If it’s more than $50,000, you’re a semiweekly depositor.1Internal Revenue Service. Notice 931 – Deposit Requirements for Employment Taxes
What the Lookback Period Actually Measures
Every employer that files Form 941 reports federal income tax withheld, Social Security tax, and Medicare tax each quarter.2Internal Revenue Service. About Form 941, Employer’s Quarterly Federal Tax Return The IRS doesn’t wait until the quarter closes to collect. It requires deposits throughout the quarter, on a rhythm tied to how much you owed during the prior 12-month stretch.
For 2026 Form 941 filers, the lookback period spans these four quarters:3Internal Revenue Service. Publication 15 (Circular E), Employer’s Tax Guide
- July 1, 2024 – September 30, 2024
- October 1, 2024 – December 31, 2024
- January 1, 2025 – March 31, 2025
- April 1, 2025 – June 30, 2025
Total the line 12 figures from those four returns. That combined number is what the IRS compares against $50,000.1Internal Revenue Service. Notice 931 – Deposit Requirements for Employment Taxes Your classification locks in before the calendar year begins and holds for the entire year. If you later file a Form 941-X to correct one of those quarters, the correction does not change your lookback calculation. The IRS uses the amounts as originally reported.
If Your Lookback Total Is $50,000 or Less: Monthly Depositor
Monthly depositors accumulate all payroll taxes from wages paid during a calendar month and deposit the total by the 15th of the following month. Taxes withheld on January paychecks are due by February 15.4eCFR. 26 CFR 31.6302-1 – Deposit Rules for Taxes Under FICA and Withheld Income Taxes When the 15th falls on a weekend or federal holiday, the deadline shifts to the next business day.
You collect and set aside withholdings across the month, then make one deposit. For businesses with modest payrolls, that rhythm generally fits typical cash flow.
If Your Lookback Total Is More Than $50,000: Semiweekly Depositor
Semiweekly depositors follow a tighter calendar tied to when employees are paid:3Internal Revenue Service. Publication 15 (Circular E), Employer’s Tax Guide
- Wages paid Wednesday, Thursday, or Friday: deposit by the following Wednesday.
- Wages paid Saturday through Tuesday: deposit by the following Friday.
The label is a little misleading. It doesn’t mean two deposits every week. It means two possible deadlines each week, and which one applies depends on your payday. If you only run payroll once in a given week, you have one deposit that period.
When the IRS determines you’ve crossed the $50,000 lookback threshold, it may send a CP236 notice reminding you of your semiweekly obligations.5Internal Revenue Service. Understanding Your CP236 Notice The reclassification is mandatory. Continuing on a monthly cadence after receiving one will produce penalties.
Two Rules That Override Your Lookback Classification
The $2,500 Quarterly Exception
If your total tax liability for either the current quarter or the preceding quarter is less than $2,500, you can skip separate deposits and pay the full amount when you file Form 941.6Internal Revenue Service. Topic No. 757, Forms 941 and 944 – Deposit Requirements This applies whether your lookback classified you as monthly or semiweekly. You lose the option if you trigger the $100,000 next-day rule during the quarter.
The $100,000 Next-Day Deposit Rule
If you accumulate $100,000 or more in tax liability on any single day, you must deposit the full amount by the close of the next business day.3Internal Revenue Service. Publication 15 (Circular E), Employer’s Tax Guide This overrides both the monthly and semiweekly schedules and applies regardless of your lookback classification.
The rule also carries a lasting consequence. Hitting the threshold immediately reclassifies you as a semiweekly depositor for the rest of the current calendar year and the entire following year.4eCFR. 26 CFR 31.6302-1 – Deposit Rules for Taxes Under FICA and Withheld Income Taxes The reclassification is automatic, and it happens no matter what your lookback total showed.
How the threshold is measured depends on your current status. Monthly depositors look at accumulated liability across the entire calendar month. Semiweekly depositors look only at the current semiweekly period, either Wednesday through Friday or Saturday through Tuesday.
New Employers and Acquired Businesses
If your business didn’t exist for the full lookback period, the IRS treats every quarter before you started as zero. In practice, that makes new employers monthly depositors for their first calendar year.1Internal Revenue Service. Notice 931 – Deposit Requirements for Employment Taxes
The same treatment applies if you acquired an existing business partway through the lookback period. Your pre-acquisition quarters count as zero. The $100,000 next-day rule still applies from day one, though. A new employer with a large first payroll can be pushed into semiweekly status mid-year.
A Different Lookback for Form 944 Filers
The smallest employers, those with $1,000 or less in annual payroll tax liability, may qualify to file Form 944 once a year instead of Form 941 each quarter.7Internal Revenue Service. About Form 944, Employer’s Annual Federal Tax Return The IRS has to notify you that you’re eligible; you can’t switch on your own.
The lookback period for Form 944 filers works differently. Instead of a July-to-June window across four quarters, it’s the entire calendar year two years prior. For 2026, that means calendar year 2024.6Internal Revenue Service. Topic No. 757, Forms 941 and 944 – Deposit Requirements The same $50,000 threshold applies once the lookback total is set. If you filed Form 944 in either 2024 or 2025 but are filing Form 941 for 2026, your lookback period is still calendar year 2024.3Internal Revenue Service. Publication 15 (Circular E), Employer’s Tax Guide
Why Getting the Classification Right Matters
The lookback period isn’t just an accounting exercise. It sets the deadlines you’ll be measured against for a full calendar year, and missing them triggers the failure-to-deposit penalty. The rate climbs the longer a deposit is late:8Office of the Law Revision Counsel. 26 USC 6656 – Failure to Make Deposit of Taxes
- 1–5 calendar days late: 2% of the unpaid amount
- 6–15 calendar days late: 5%
- More than 15 calendar days late: 10%
- Still unpaid 10 days after the IRS sends a delinquency notice, or upon receiving an immediate payment demand: 15%
On a $20,000 deposit, even the lowest tier is $400. Penalties apply per missed deposit, so an employer who misreads the lookback result and stays on a monthly schedule after being reclassified as semiweekly can rack up penalties on every payroll through the quarter. Running the calculation carefully at the start of the year, and rerunning it any time a large single-day liability comes through, is the whole point of the exercise.