Four-Day Workweek Compliance Guide for Employers (2026)

Four-day workweeks have moved from experimental pilot to mainstream HR policy in record time. Belgium and Japan have introduced laws for these schedules, while employers in cities such as London and Los Angeles have adopted them in response to retention pressure and productivity research. What the headlines rarely cover is what happens inside the payroll system the day a new schedule goes live.

The compliance blind spot isn't the schedule itself. It's the reconfiguration layer underneath: overtime threshold calculations that shift when daily hours change, holiday pay averaging formulas that depend on the working pattern you're replacing, and benefits eligibility thresholds that key off hours or earnings in ways a four-day week can quietly breach. For employers operating across multiple countries, each jurisdiction applies its own rules to these mechanics, and no single global policy covers all of them.

This guide explains what changes, and what payroll leaders must reconfigure, in the United States, Belgium, Japan, and the United Kingdom before a four-day workweek goes live.

What a four-day workweek actually means for payroll

The term "four-day workweek" describes two structurally different arrangements, and the distinction drives entirely different compliance obligations.

A compressed workweek keeps total weekly hours the same but redistributes them across fewer days. The classic model is 4x10: four 10-hour days adding up to the standard 40 hours. Total compensation stays flat, but daily hours increase. In some jurisdictions, that daily increase directly triggers overtime or rest-period obligations regardless of the weekly total.

A reduced-hour workweek cuts actual working time, typically to 32 hours, while maintaining the same salary. The weekly total drops, which can push employees below the minimum-hours thresholds that determine full-time status, benefits eligibility, and social contribution tiers.

Getting the model right matters before touching anything else. Misclassifying a compressed schedule as equivalent to a reduced-hour schedule will produce the wrong overtime calculations, the wrong benefits eligibility assessments, and the wrong contract language from the start.

How overtime thresholds shift under a four-day schedule

The four jurisdictions below each apply a distinct overtime framework, and a four-day schedule interacts with each one differently. Here's how payroll teams should read each one.

United States: Fair Labor Standards Act

Under the Fair Labor Standards Act, overtime is triggered by hours worked in excess of 40 in a single workweek. For a 4x10 compressed schedule, the total remains exactly 40 hours, so no federal overtime is triggered. A genuine 32-hour reduced-hour week eliminates federal overtime exposure entirely.

The critical caveat is California. California imposes daily overtime after eight hours worked in a day and double-time after 12 hours. A 4x10 compressed schedule produces two extra hours of daily overtime every day the employee works, unless the employer has adopted a valid alternative workweek arrangement under California Labor Code Section 511. That arrangement requires a two-thirds majority vote by the affected work unit and advance notice filing with the Division of Labor Standards Enforcement. Without that arrangement, a 4x10 schedule triggers daily overtime in California regardless of the federal 40-hour rule.

Other states with daily overtime rules, including Alaska and Nevada, require the same analysis before a compressed schedule goes live.

Belgium

Belgium's standard statutory working week is 38 hours. Employers who want to implement a four-day compressed week may do so under the 2022 Labour Deal, which allows employees to request a compressed schedule without reducing their total hours. The practical effect is a longer working day: up to 9.5 hours under the standard statutory ceiling, or up to 10 hours if a collective bargaining agreement (CBA) permits it.

The key compliance question is whether the agreed daily hours stay within those ceilings. A compressed four-day week that pushes daily hours above the applicable limit triggers Belgian overtime obligations, which require a CBA or individual agreement and additional compensation. Belgian overtime rules also apply daily limits, so employers can't offset one long day with shorter days in the same week.

For global overtime rules across multiple countries, employers managing cross-border workforces need jurisdiction-specific configurations, not a single global standard.

Japan

Japan's Labor Standards Act sets a 40-hour weekly cap and an eight-hour daily cap. A four-day schedule that redistributes hours into longer working days will exceed the daily eight-hour limit on each of those four days, even if the weekly total stays within 40 hours. That excess requires an advance written agreement between the employer and an employee representative or labor union: the Article 36 Agreement (sanroku kyotei), filed with the local Labor Standards Office before any overtime work is performed.

This means a Japanese employer cannot simply announce a 4x10 schedule and begin operations. The Article 36 Agreement must be in place first, specifying the scope and conditions of any overtime. A four-day schedule can still trigger overtime under Japan's Labor Standards Act.

United Kingdom

The UK's Working Time Regulations cap average weekly working time at 48 hours, measured over a 17-week reference period. A 4x10 compressed schedule totals 40 hours, well below that cap, so the weekly limit is not the primary compliance concern.

The real risks lie in daily rest and break entitlements. Workers are entitled to 11 consecutive hours of rest between working days and a 20-minute rest break if the working day exceeds six hours. A 10-hour working day satisfies both requirements if scheduled correctly, but employers must confirm rest periods are actually provided, not just planned, before switching schedules. Workers who have not signed an opt-out agreement are also protected by the 48-hour average, so employers should track hours carefully if any compressed-schedule variation results in weeks that exceed that figure.

Holiday pay recalculation when the week changes

Switching the working pattern doesn't just change how many days an employee works. It changes the baseline against which holiday entitlement and holiday pay are calculated, and each jurisdiction handles this differently.

United Kingdom

Under the Working Time Regulations, workers are entitled to a week's pay for each week of statutory leave they take. For regular-hours workers, holiday pay equals a week's pay. For irregular-hours workers, holiday pay is calculated as an average of actual pay over the previous 52 paid weeks, counting only weeks in which pay was actually received.

When an employee moves from a five-day to a four-day pattern, the entitlement calculation changes: a four-day worker is entitled to 5.6 weeks of statutory leave, but "a week" now means four working days rather than five. The employee effectively accrues fewer calendar days of leave than a five-day equivalent. If the employment contract was written on a five-day basis and is not updated to reflect the new pattern, the employer may be paying out holiday on the wrong basis. Employers should amend contracts when the existing terms no longer match the employee's working pattern.

Belgium

Belgium's statutory annual leave entitlement is calculated on a five-day reference week: a full-time employee working five days per week receives up to 20 business days of vacation. Because entitlement is measured in working days, a compressed four-day week where total hours remain the same does not automatically reduce the number of days. However, if the employment contract and leave policy are not updated to reflect the new pattern, there is a risk of misapplication, particularly for partial-year accruals and pro-rata calculations.

The more significant issue arises when a public holiday falls on the employee's designated off day, typically Friday. Belgian law does not automatically grant a substitute day off for a public holiday that falls on a non-working day, unless the employment contract or CBA specifies otherwise. Employers must audit their leave policies and public holiday provisions before the new schedule takes effect.

Japan

Japan's minimum statutory annual leave entitlement begins at 10 days for employees who have completed six months of continuous employment and worked at least 80% of scheduled working days. Leave is granted and measured in working days. Under a four-day workweek, the number of working days in a year decreases, which changes how many leave days constitute a meaningful proportion of working time.

The practical risk applies to employees whose leave accrual is calculated against their working pattern. If an employee moves to a four-day week mid-year, their accrual for the remainder of the leave year must be recalculated against the new pattern. Payroll systems that carry the old daily structure forward without adjustment will produce incorrect accrual figures.

United States

There is no federal statutory paid holiday mandate in the United States. Employers designate their own holidays and set their own substitution policies. When a compressed workweek makes Friday a non-working day, and Friday happens to be a designated company holiday, employers face a consistency problem: does the employee receive a substitute day off, or does the holiday simply disappear?

The answer depends entirely on the employer's policy language. If the policy is silent on substitution, the employer may face inconsistency claims or equal-treatment complaints from employees on different schedules. Policy documents must be updated to state explicitly how holidays that fall on a non-working day are handled under each schedule variant in use.

Benefits eligibility: where hours-based thresholds create exposure

For enterprise payroll compliance across multiple countries, benefits eligibility is where reduced-hour models create the most significant legal exposure.

ACA employer shared responsibility (United States)

Under the Affordable Care Act (ACA), an employee averages at least 30 hours of service per week to qualify as a full-time employee for employer shared responsibility purposes. Applicable Large Employers (ALEs), generally employers with 50 or more full-time equivalent employees, must offer affordable, minimum-value health coverage to their full-time employees or face a shared responsibility payment.

A genuine 32-hour four-day workweek sits directly at this threshold. Whether an employee averaging 32 hours per week counts as full-time depends on the employer's measurement method: the monthly measurement method counts hours each month, while the look-back measurement method assesses an employee's average over a defined measurement period. The look-back method can produce a different full-time determination than a month-by-month count. ALEs implementing a 32-hour schedule must audit their measurement methodology and confirm that their tracking systems capture the new hours accurately.

Social security and pension contributions

Contribution thresholds in Belgium, the UK, and Japan all key off either earnings or hours in ways that a reduced-hour model can affect.

In the UK, the auto-enrolment qualifying earnings threshold for workplace pension contributions applies to earnings above £6,240 per year (for 2024/25). A reduced-salary four-day week that brings an employee below this threshold removes the auto-enrolment trigger. This relieves the employer of its contribution obligation and removes the employee from pension saving, which may or may not be the intended outcome, but it is a compliance consequence that must be tracked.

In Belgium, social security contributions are calculated on actual remuneration. A reduced-hour, reduced-salary model lowers the contribution base and may affect the employee's social security entitlement calculations for future benefits such as unemployment and disability. Employers should document the change and its basis before the new schedule begins.

In Japan, the shakai hoken (social insurance) coverage threshold requires an employee to work at least 20 hours per week and earn at least ¥88,000 per month to qualify for coverage at companies of certain sizes. A four-day model that reduces hours below the 20-hour threshold removes the employee from shakai hoken coverage. That is a significant change requiring explicit notification and employee consent under Japanese employment law.

Other hours-tied entitlements

Sick pay eligibility, parental leave qualifying conditions, and union or CBA entitlements across multiple jurisdictions are tied to contracted hours. A change in contracted hours, even without a change in salary, can affect these entitlements without any intent on the employer's part. All affected employees should receive written notification of how their hours change affects, or does not affect, each entitlement. This is a documentation obligation, not just a courtesy.

What payroll leaders must reconfigure before go-live

A four-day workweek rollout is not a scheduling change with a payroll consequence. It's a payroll reconfiguration with a scheduling announcement attached. The following checklist covers the minimum technical and administrative steps required before the new schedule is active.

• Update employment contracts to reflect the new working pattern, daily hours, and any change to weekly hours. In the UK and Belgium particularly, the working pattern is a contractual term, and changing it without written agreement carries legal risk.

• Reconfigure overtime logic for each affected jurisdiction. A payroll system that applies a 40-hour weekly trigger for every country will not capture Belgian daily ceilings, California's daily rules, or Japan's eight-hour daily limit correctly.

• Update the working-days-per-week parameter in your leave management system. A system calculating holiday entitlement on a five-day default will over-accrue leave for four-day workers.

• Review health insurance plan documents, pension scheme rules, and any other benefits with hours-based eligibility triggers. Confirm whether the new schedule changes eligibility status and update plan documents accordingly.

• Ensure your time-tracking system captures actual daily hours, not just weekly totals, for jurisdictions where daily overtime limits apply.

• Provide written notification of the schedule change, its effective date, and how each benefit and entitlement is affected. This is legally required in many jurisdictions and good practice in all of them.

For a detailed global payroll compliance checklist across jurisdictions, the pre-go-live review should also cover local employment registration requirements and any mandatory notification deadlines.

Stay compliant with Deel Payroll and Deel HR

For employees hired through your own entities, Deel Payroll supports payroll operations across multiple jurisdictions, helping payroll teams manage country-specific requirements within a connected platform. When a four-day workweek changes working-hours structures across countries, Deel Payroll can help teams keep their payroll configurations aligned with their workforce's actual arrangements.

Deel HR serves as the lifecycle system after hire, helping teams maintain workforce information as working arrangements change. Because Deel HR and Deel Payroll are part of the same connected platform, workforce and payroll data can remain aligned across relevant workflows, rather than requiring a manual sync between disconnected systems.

Managing part-time holiday pay obligations across multiple countries is one of the most frequently missed steps in a four-day workweek rollout. With Deel, global teams can manage country-specific rules without maintaining separate local tools for each jurisdiction.

Book a demo to see how Deel Payroll and Deel HR can support your four-day workweek rollout across multiple jurisdictions.