For accountants · 3 min read
The real cost of the 40-hour workweek for a small and mid-sized business
Short answer
The wage does not drop and the hours do, so the cost per hour worked goes up. From 48 to 46 hours the increase is 4.3%; from 48 to 40, 20%.
The calculation
Cost per hour = weekly wage ÷ hours in the week. With the same wage, 48 ÷ 46 = 1.043 and 48 ÷ 40 = 1.20.
What decides the final impact
- Whether the company needs to cover the hours that are lost.
- Whether it covers them with relief staff or with overtime.
How to do the math by hand
With 10 people working 48 hours and a maximum of 46, that is 2 hours per person: 20 hours per week to cover.
The reform in one minute
The reform has two parts. On March 3, 2026, article 123 of the Constitution was amended to set the 40-hour workweek. On May 1, 2026, the Federal Labor Law was amended, which is where the detail is.
- The maximum working week drops from 48 to 40 hours, two hours per year, between 2027 and 2030.
- Overtime has a weekly cap: it is paid at double time up to the cap and at triple time for up to 4 more hours.
- Each company must electronically record the start and end time of each person's workday.
- Not keeping that record is fined 250 to 5,000 UMA.
- Salary and benefits cannot go down because of the reduction in hours.
What remains pending are the STPS general rules, which will define who the record applies to and what exceptions there will be. They take effect on January 1, 2027.
| Year | Maximum working hours | Double-time overtime | Triple-time overtime |
|---|---|---|---|
| 2026 | 48 h | 9 h | 4 h |
| 2027 | 46 h | 9 h | 4 h |
| 2028 | 44 h | 10 h | 4 h |
| 2029 | 42 h | 11 h | 4 h |
| 2030 | 40 h | 12 h | 4 h |
Decree published in the Official Gazette of the Federation on May 1, 2026, second and fourth transitory provisions, and article 68 of the LFT. Each change applies from January 1.
Common mistakes
- Calculating payroll with the hours the client remembers.
- Averaging overtime across weeks.
- Not warning the client when the record and the payslip do not match.
- Treating the record as a topic for the lawyer only.
- Waiting for the client to ask.
What to do now
- List your clients who have employees.
- Ask each one how they record working time.
- Send them a summary of the reform.
- Review their overtime from the last month against the new caps.
- Recommend an electronic record to them and ask for view access.
Related terms
Vacations by law: how many days are owed. With one year of work, 12 days of vacation are owed.
IMSS contributions: what they are and who pays them. Employer-employee contributions are the payments to the IMSS that fund social security.
What is attendance control. Attendance control is any means of knowing who came to work and at what time.
Frequently asked questions
Does the cost of overtime also go up?
Yes, because they are calculated on an hour that is worth more.
Is overtime counted by week?
Yes. The cap on double-time overtime is weekly and per person.
Can someone work more than 12 hours in a day?
No. The sum of ordinary and overtime hours cannot exceed 12 hours per day.
Does salary go down if fewer hours are worked?
No. The reform prohibits lowering wages and benefits because of the reduction in working hours.
Is the reform already in force?
Yes. The reform to the Federal Labor Law took effect on May 1, 2026. The reduction in working hours starts on January 1, 2027.
Legal basis and sources
- Working hours: articles 58 to 64 of the LFT and second transitory provision of the decree.
- Decree amending the Federal Labor Law on the reduction of the working week. Official Gazette of the Federation, May 1, 2026.
- Federal Labor Law, current text. Chamber of Deputies.
How we write this content. The Sicheca team writes it from the official text of the law. When something is not yet defined by the authority, we say so. It is general information and does not replace the advice of a lawyer or an accountant.