Formal salary scales can make a workplace look more equal than it really is.
A new analysis of 10,291 employees in a large municipal workforce found that women earned 94.7 cents for every dollar of men’s base salary, but only 86.3 cents for every dollar of men’s total compensation once overtime and longevity pay were included. The difference was driven mainly by overtime access rather than the published salary structure.
The study, published on 6 October 2026 in Humanities and Social Sciences Communications, examined pay across 42 departments and 627 divisions. Men were more than twice as likely as women to receive overtime, and the resulting overtime gap accounted for 61.6% of the overall difference in total compensation.
The findings matter beyond one municipality. They show why organisations can satisfy formal equal-pay rules and still produce unequal earnings through the less visible decisions that determine who gets extra hours, shifts and supplemental compensation.
More than 10,000 employee records were analysed
The researchers analysed administrative payroll data for 10,291 employees. The workforce was 58% male, with 5,929 men, and 42% female, with 4,362 women. Employees were spread across 42 departments and 627 divisions.
Rather than examining salary alone, the researchers constructed total compensation from three components: base salary, overtime pay and longevity pay. This distinction was central to the study because a narrow comparison of salary scales can miss inequalities that emerge after employees enter formally equivalent pay systems.
The analysis compared pay gaps, female-to-male pay ratios, access to overtime and department-level differences. Detailed department comparisons were restricted to departments containing at least 10 employees of each gender. That left 26 departments representing 9,847 employees, or 95.7% of the workforce.
The researchers also used a multivariate analysis of variance to test whether the overall compensation profile differed by gender. The multivariate result was statistically significant, with Pillai’s Trace of 0.043, F(3,10287) = 154.27 and p < 0.001. Follow-up tests found significant gender differences in each of the three compensation components.
The salary gap was 5.6%, but the total compensation gap reached 15.9%
At the base-salary level, the difference was comparatively modest. Women earned 94.7 cents for every dollar earned by men, corresponding to a reported base salary gap of 5.6%.
Once overtime and longevity compensation were included, the gap widened sharply. Women received 86.3 cents for every dollar of men’s total compensation, producing a total compensation gap of 15.9%.
That widening is one of the study’s most important findings. It means that focusing exclusively on base salary would substantially understate the earnings difference observed in this workforce.
The pattern also complicates a common assumption about structured public-sector pay. Standardised grades and salary schedules can constrain some forms of unequal pay, but they do not necessarily control access to variable compensation.
Overtime explained 61.6% of the overall compensation gap
The largest disparity appeared in overtime.
Among male employees, 4,155, or 70.1%, received overtime compensation. Among female employees, 1,485, or 34.0%, received it. That is a 36.1 percentage point difference in access.
Across all employees, men received an average of $11,873 in annual overtime pay compared with $2,928 for women. The average difference was $8,945.
The researchers calculated that this overtime difference accounted for 61.6% of the total $14,525 compensation gap between male and female employees. Expressed another way, men’s average overtime compensation was about 306% higher than women’s when the male amount was compared with the female amount.
The study therefore points to two related questions for employers. The first is how much overtime pays. The second, and arguably more important one in this dataset, is who gets access to it in the first place.
Longevity pay contributed a smaller but still substantial difference
Longevity compensation was more evenly accessible than overtime, but its average amounts still differed.
Men received an average of $1,828 in longevity pay compared with $1,134 for women, a difference of roughly 61%. Access rates were much closer: 29% of men and 26% of women received longevity pay.
This contrasts with overtime, where the access gap itself was enormous. It suggests that different components of compensation may require different explanations and different policy responses.
Base salary differences may direct attention to classification and promotion. Longevity differences may raise questions about tenure and career interruption. Overtime disparities require scrutiny of eligibility, scheduling and supervisory allocation decisions.
Pay gaps varied dramatically between departments
The overall averages concealed large differences within the organisation.
Across the 26 departments with sufficient numbers of men and women for detailed analysis, female-to-male total compensation ranged from 113% at one end to 66% at the other. Four departments recorded higher average total compensation for women than men.
The Department of Recreation produced the most female-favouring result, with women receiving 113% of men’s compensation. At the other extreme, the Department of Police, which included 1,794 employees, showed a 38% total compensation gap.
Across the 26 departments, the average base salary gap was 7% and the average total compensation gap was 9%, but individual departmental gaps ranged from negative 12% to positive 50%.
That variation is important because all of these departments operated inside the same wider municipal system. A single central compensation framework therefore did not produce uniform outcomes. Local job composition, scheduling practices, operational requirements, management and departmental culture may all matter.
Equal base salaries did not reliably predict equal total pay
The researchers reported only a weak relationship between departmental base-salary equity and total-compensation equity.
Some departments with relatively equitable base salaries developed much larger total-pay gaps after overtime was added. Other departments reached relatively equitable total compensation through different combinations of salary and supplemental pay.
This means a pay-equity audit based only on headline salaries could classify a department as comparatively equitable while missing a large difference in actual annual earnings.
The study also examined whether the gender difference persisted after accounting for civil-service grade and tenure. In an ordinary least squares model using log total compensation, gender remained a statistically significant predictor after those controls, with a coefficient of 0.089, standard error of 0.006 and p < 0.001.
This does not prove discrimination. It does show that the observed male advantage in total compensation was not fully accounted for by the available measures of job level and seniority.
Why overtime can become an equity blind spot
Overtime is often treated as operational rather than strategic. A department needs additional coverage, a supervisor allocates a shift, and payroll records the extra hours. Repeated across thousands of decisions, however, these allocations can become a major component of annual income.
The study’s results show how a relatively small base-salary gap can expand when one group has substantially greater access to additional paid work.
There are several possible mechanisms. Different occupations can have different overtime requirements, men and women may be unevenly distributed across those occupations, employees may differ in their availability or willingness to work additional hours, and supervisors may allocate opportunities differently. The administrative data cannot fully separate these explanations.
That uncertainty is precisely why the authors argue for component-level monitoring. An organisation that tracks only total payroll or formal salary bands may not see where a disparity is being generated.
The findings do not establish why the gap occurred
The study has important limitations.
First, it is a cross-sectional analysis of one municipal workforce. It identifies compensation patterns at one point in time and cannot establish that particular management practices caused the observed gender differences.
Second, the administrative data did not include employees’ preferences, availability for overtime, work-life constraints or decisions about additional shifts. These factors could contribute to differences in overtime participation.
Third, occupational segregation is difficult to disentangle from allocation practices. If men are concentrated in jobs that structurally generate more overtime, part of the gap may reflect job composition rather than supervisors choosing men over women for equivalent opportunities.
Fourth, the study comes from a single municipal organisation. Its precise percentages should not be assumed to describe other municipalities, private-sector employers or countries with different labour systems.
Finally, civil-service grade was used as a proxy for occupational position, but grade itself may not capture every relevant difference in role, responsibility, shift pattern or promotion history. Grade information was also unavailable for 33 employees.
The practical lesson is to audit the whole payslip
The findings suggest that pay-equity analysis should extend beyond basic salary.
For employers, a useful audit would separately examine who is eligible for overtime, who is offered it, who accepts it, how much is worked, how those patterns differ within comparable roles and whether particular supervisors or divisions produce persistent disparities.
The same logic applies to bonuses, commissions, allowances, shift premiums and other forms of variable compensation. A formal salary structure can be equitable while the system that sits around it produces a very different outcome.
The departmental variation also offers a practical research strategy. Rather than treating the organisation as one homogeneous workplace, employers can compare units with unusually large gaps against units that achieve closer parity and investigate which scheduling, staffing and management practices differ.
The study ultimately makes a simple point with unusually detailed payroll evidence: what employees are paid cannot be understood from salary alone. In this municipal workforce, women were relatively close to men on base pay, but the gap nearly tripled when the full compensation package was considered. Most of that widening was associated with overtime.
Source Information
Study: Ayse Ilgun Kamanli and Yavuz Selim Balcıoğlu, “Gender pay equity in public sector employment: An analysis of compensation disparities and overtime allocation across municipal departments.”
Journal: Humanities and Social Sciences Communications, volume 13, article 1703.
Published: 6 October 2026.
DOI: 10.1057/s41599-026-08737-0.
Study design: Cross-sectional administrative payroll analysis of 10,291 employees across 42 departments and 627 divisions, with compensation decomposed into base salary, overtime and longevity pay. Detailed departmental analysis covered 9,847 employees in 26 departments meeting the minimum gender sample criterion.
Important limitation: The study identifies associations and compensation patterns, not causal evidence that gender itself or discriminatory decisions caused the observed differences.
