1. Structural Comparison: 4/10 vs 9/80 vs Traditional 5/8
Compressed workweeks repackage the standard 80-hour biweekly full-time workload into fewer commuting days without cutting base compensation. Under a 4/10 schedule, employees complete four 10-hour shifts every week (typically Monday–Thursday or Tuesday–Friday), earning 52 three-day weekends annually. Under a 9/80 schedule (called 5/4-9 in federal OPM terminology), employees work eight 9-hour days Monday–Thursday plus one 8-hour Friday in Week 1, earning the second Friday off for 26 three-day weekends annually.
| Workweek Attribute | 4/10 Compressed | 9/80 Compressed | Standard 5/8 Baseline |
|---|---|---|---|
| Daily Paid Shift | 10.0 hours (Mon–Thu) | 9.0 hrs (M–Th) & 8.0 hrs (Alt Fri) | 8.0 hours (Mon–Fri) |
| Total Door-to-Door Day (w/ 30m Lunch) | 10.5 hours on-site (e.g., 06:30–17:00) | 9.5 hours on-site (e.g., 07:30–17:00) | 8.5 hours on-site (e.g., 08:00–16:30) |
| Calendar Clock Hours (Wk 1 / Wk 2) | 40h / 40h | 44h / 36h | 40h / 40h |
| 3-Day Weekends / Year | 52 per year (every week) | 26 per year (every 2 weeks) | 0 (holidays only) |
| Commute Reduction | -52 round trips/yr (-20%) | -26 round trips/yr (-10%) | 260 round trips/yr baseline |
| Department Coverage Strategy | Split team: Mon–Thu vs Tue–Fri | Split team: Track A vs Track B Fridays | 100% Mon–Fri coverage |
2. Avoiding the 9/80 FLSA Workweek Split Trap
From a payroll engineering standpoint, 4/10 is plug-and-play in 46 US states: because four 10-hour days total 40.0 hours inside a standard Sunday-to-Saturday workweek, non-exempt employees incur zero federal overtime. By contrast, launching a 9/80 schedule without reconfiguring your payroll timekeeping boundary creates an immediate federal wage-and-hour violation.
Under 29 CFR § 778.104, each 168-hour statutory workweek stands alone—employers may never average a 44-hour week and a 36-hour week across a biweekly pay period. As detailed in our 9/80 Work Schedule Guide, HR must permanently define the employee’s 168-hour statutory workweek under 29 CFR § 778.105 to begin and end exactly 4.0 work hours into the working Friday (for example, Friday at 12:00 PM if morning hours run 07:30–11:30):
| FLSA Workweek Window | Fri PM | Mon | Tue | Wed | Thu | Fri AM | Statutory Total |
|---|---|---|---|---|---|---|---|
| Statutory Week 1 (Ends Working Fri 12:00 PM) | 0h (Off) | 9h | 9h | 9h | 9h | 4h | 40.0h (0h OT) |
| Statutory Week 2 (Starts Working Fri 12:00 PM) | 4h | 9h | 9h | 9h | 9h | 0h (Off) | 40.0h (0h OT) |
Operational Caution: Employees on 9/80 cannot casually swap their Flex Friday off from Week 2 to Week 1 without triggering 4 hours of statutory overtime, because changing which Friday is worked breaks the fixed Friday 12:00 PM boundary!
3. California Daily Overtime (AWS Secret-Ballot Rules) & Holiday PTO Math
State Daily Overtime & California AWS Elections
While federal law only taxes hours over 40 per week, California (Labor Code §§ 510–511), Alaska, and Nevada enforce 8-hour daily overtime (and Colorado enforces a 12-hour daily cap). In California, non-exempt workers on 4/10 or 9/80 earn 1.5× daily overtime after 8 hours unless the employer adopts a formal Alternative Workweek Schedule (AWS): delivering written disclosures, holding an employee meeting at least 14 days prior, winning a 2/3 secret-ballot vote of affected employees in the work unit, and filing election results with the California DIR within 30 days. Even with an approved AWS, work past the scheduled 9 or 10 daily hours triggers 1.5× pay, and hours past 12/day require 2.0× double time.
Holiday Credit Accounting (8h vs 9h/10h Deficit)
Most private US companies budget 80 holiday hours per year (10 holidays × 8.0 hours). When Labor Day or Memorial Day lands on a Monday, an 8-hour holiday credit leaves a 2-hour deficit on 4/10 or a 1-hour deficit on 9/80. HR policies resolve this by either auto-deducting 1–2 hours of PTO, letting staff work 1–2 extra hours across the remaining three days of that same FLSA workweek, or matching shift length (standard for federal employees under 5 U.S.C. § 6124). When a holiday lands on a scheduled Friday off, employees receive an in-lieu-of holiday on Thursday or an 8-hour floating holiday credit.
4. Cohort Coverage Design, Exempt Salary Rules & Transition Audits
Rolling out a compressed workweek without disrupting Monday-through-Friday client SLA targets requires deliberate cohort balancing and careful transition-week payroll handling:
- 5-Day Coverage Pairing: On 4/10, operations managers assign 50% of staff to Cohort A (Mon–Thu, 40h) and 50% to Cohort B (Tue–Fri, 40h)—delivering 100% staffing Tuesday through Thursday and 50% coverage on Mondays and Fridays. On 9/80, pairing Track A (Week 1 Flex Friday off) with Track B (Week 2 Flex Friday off) keeps 100% of staff present Monday through Thursday every single week and 50% present every Friday.
- Transition-Week Overtime Overlap (29 CFR § 778.301): When migrating an existing non-exempt team from a Sunday-midnight workweek to a Friday 12:00 PM 9/80 workweek, the old and new 168-hour windows temporarily overlap across Monday through Friday morning. Under Department of Labor overlap calculation rules, payroll must compute hours under both boundaries during the cutover week and pay whichever calculation yields higher overtime.
- Salaried Exempt PTO Deductions (29 CFR § 541.602): Employers may deduct 9 or 10 hours from a salaried exempt employee’s paid leave bank for a full day’s absence without jeopardizing exempt salary-basis status, provided cash salary is never docked for partial-day absences when PTO banks are exhausted.
Build & Export Your Compressed Workweek Calendar
Preview every 3-day weekend in 2026–2027 and export ICS/CSV files for Outlook, Google Calendar, or Apple Calendar.