Strengthening Work Incentives for Second Earners in Japan

 In Japan’s current tax-benefit system, secondary earners—primarily mothers with young children—face significant financial disincentives to either entering the workforce or increasing their earnings. These disincentives stem from two main features: spousal tax allowances and stepwise childcare fees.

Spousal Tax Allowances

The personal income tax system provides allowances to primary earners whose spouses earn below a specific income threshold.

• Structure: There is a flat-rate allowance for very low earnings and a "special" tapered allowance that decreases as the spouse's income rises.
• The Disincentive: Because these allowances phase out as the secondary earner makes more money, they create a "financial penalty" for working.
• Impact on Incentives:
  • Extensive Margin (Entering Work): The withdrawal of these allowances increases the participation tax rate (PTR), meaning a larger portion of a new job's earnings is lost to higher taxes.
  • Intensive Margin (Earning More): The stepwise withdrawal of the flat-rate allowance causes sudden spikes in marginal effective tax rates (METRs). This non-linear pattern makes it difficult for families to anticipate financial returns and discourages second earners from working just above the phase-out threshold.

Stepwise Childcare Fees

For children under the age of three, public childcare subsidies follow a "stepwise" fee schedule based on household income.

• Structure: Parental contributions do not rise smoothly; instead, they jump abruptly once household income crosses certain thresholds.
• The Disincentive: These sudden hikes significantly reduce the net financial return for marginal increases in income.
• Impact on Incentives:
  • Unpredictability: The structure makes it very difficult for families to predict the cost of increasing their earnings, as a small raise could trigger a disproportionately large jump in childcare costs.
  • METR Spikes: Similar to the tax allowances, these sudden fee increases create sharp spikes in METRs at the threshold points.

Broader Context: Strengthening Work Incentives

The sources argue that these two features combined mean the financial return for mothers entering or expanding their employment is relatively low. This system acts as a structural factor contributing to gender disparities in Japan’s employment outcomes.

To strengthen work incentives, the sources evaluate two primary reforms:

1. Removing Spousal Tax Allowances: This would simplify the tax system and provide a more stable financial return across all earnings levels.
2. Linearizing Childcare Fees: Replacing the steps with a gradually tapering schedule would make costs predictable and eliminate sudden price hikes.

Together, these reforms are intended to address the tax-side and spending-side penalties that currently discourage second earners from full-time employment.

Reform 1 proposes the complete removal of both flat-rate and tapered (“special”) spousal tax allowances under Japan’s national and local income tax schemes. Within the larger goal of strengthening work incentives, this reform is designed to address a major tax-side disincentive where the current system effectively penalizes secondary earners for entering the workforce or increasing their hours.

According to the source, the impacts of this reform are seen across two primary dimensions:

Strengthening Incentives to Enter Work (Extensive Margin)

Currently, the way spousal allowances phase out adds to the tax increases and benefit losses a secondary earner faces when they first take a job. This creates a high Participation Tax Rate (PTR), which acts as a "financial penalty" for entering employment.

• The Reform's Impact: Removing these allowances would lower PTRs across the withdrawal range.
• Outcome: By eliminating the penalty, the reform makes the decision to start working more financially attractive for secondary earners, primarily mothers.

Strengthening Incentives to Earn More (Intensive Margin)

Under the current system, the stepwise withdrawal of the flat-rate allowance creates sharp spikes in Marginal Effective Tax Rates (METRs) at specific income thresholds. These spikes make it difficult for families to predict their net income and discourage second earners from working just above the phase-out points.

• The Reform's Impact: Total removal would eliminate these METR spikes, resulting in a more stable and linear financial return to work across all earnings levels.
• Outcome: Second earners would face fewer distortions when deciding whether to increase their hours or pursue higher-paying positions.

Broader Structural and Combined Effects

Beyond immediate financial metrics, the sources highlight several strategic benefits of Reform 1:

• System Simplification: Removing these complex, layered allowances would significantly simplify the Japanese income tax system.
• Addressing Gender Disparities: The reform is described as a way to remove a structural factor that contributes to gender disparities in Japan's employment outcomes.
• Synergy with Childcare Reform: When combined with Reform 2 (linearizing childcare fees), the removal of spousal allowances amplifies the gains at higher earnings levels. While it may slightly increase childcare costs for those at the lowest part-time earnings levels (by increasing the reference income used for fee calculations), it provides a clearly stronger incentive to take up full-time employment at average or above-average wage levels.

Reform 2 proposes replacing the current stepwise childcare fee schedule for children under the age of three with a linearly tapering fee. Within the larger objective of strengthening work incentives for second earners, this reform addresses a major spending-side disincentive where the current system penalizes families for marginal income gains.

The sources highlight several key aspects and impacts of this reform:

Improving Predictability and Reducing Costs

The current system causes childcare fees to "jump abruptly" as a household crosses specific income thresholds.

• Smoothing Costs: Reform 2 would ensure fees rise gradually and smoothly with income, making childcare costs far more predictable for families.
• Lowering Net Costs: The reform is designed to reduce net childcare costs across the earnings range. For a couple where one parent earns the minimum wage and the secondary earner makes 67% of the average wage, net costs would drop from 13.1% to 8.5% of the average wage.
• Narrowing the International Gap: While Japan’s net childcare costs would remain above the OECD average (7.3%), this reform would significantly narrow the gap, particularly for lower-income families.

Strengthening Work Incentives

The reform targets distortions at both the extensive and intensive margins:

• Extensive Margin (Entering Work): By lowering the overall cost of childcare, the reform reduces the Participation Tax Rate (PTR). This makes the decision to enter employment more financially rewarding for second earners.
• Intensive Margin (Earning More): The reform eliminates the sharp spikes in Marginal Effective Tax Rates (METRs) currently caused by threshold jumps.
  • The Trade-off: Because the subsidy is phased out more gradually, the source notes that secondary earners above the midpoint of the earnings range might see slightly higher METRs than under the current system, as they continue to receive a partial subsidy that slowly declines as their income rises.

Strategic Design and Synergy

• Extended Support: The linear model maintains targeted support for low-income families while extending partial subsidies further up the income scale.
• Complementary Effects: When combined with Reform 1 (removing spousal allowances), the linear childcare schedule helps create a lower and more stable METR profile. Together, these reforms address the two primary channels through which the current system penalizes secondary earners, delivering a clearly stronger incentive to take up full-time employment at average or above-average wage levels.

The sources state that applying both Reform 1 (removing spousal allowances) and Reform 2 (linearizing childcare fees) simultaneously produces complementary gains that address both the tax-side and spending-side disincentives currently penalizing second earners in Japan,.

The combined effects on work incentives are categorized as follows:

Incentives to Enter Work (Extensive Margin)

The combination of reforms generally makes entering the workforce more financially rewarding, though the impact varies by intended earnings level.

• Compounded Gains for Full-Time Work: For those entering employment at or above 32% of the average wage (roughly full-time at minimum wage), the removal of spousal allowances amplifies the gains provided by the lower childcare costs.
• The Part-Time Offset: At very low earnings levels (below 32% of the average wage), an interaction between the reforms occurs. Removing the spousal tax allowance increases the "reference income" used to calculate childcare fees, which pushes those fees upward.
• Overall Outcome: While the combined reform offers only marginal improvements for low-earnings part-time work, it delivers a clearly stronger incentive to take up full-time employment at average or above-average wage levels.

Incentives to Earn More (Intensive Margin)

The combined reforms significantly stabilize the financial return for second earners who choose to increase their hours or pursue higher pay.

• Stable Tax Profile: By eliminating the stepwise spikes from both the tax allowance phase-out and the childcare fee thresholds, the reforms create a lower and more stable Marginal Effective Tax Rate (METR) profile.
• Reduced Distortions: Secondary earners face fewer unpredictable "penalties" across the income range. The sources note that the gain is most pronounced at earnings levels that were previously hit by both the childcare fee jumps and the tax allowance withdrawal simultaneously.

Strategic Significance

The sources conclude that these reforms are complementary in design rationale. While the childcare reform reduces the net cost of working, the spousal allowance reform raises the net financial return by removing tax penalties,. Together, they address the two main channels of current system disincentives, generating work incentive gains that are greater than either reform would achieve alone for those entering full-time employment.