iDeCo and retirement-allowance timing
Overlapping service periods, lump-sum treatment, and payout sequencing.
Taking an iDeCo lump sum and a company retirement allowance both use the retirement-income deduction, and their service periods can overlap — so receiving them in the wrong order or too close together can waste the deduction; the timing should be modeled.
Effective: 2026-01-01 to 2026-12-31
Professional review pending — treat as draft and confirm with the authorities.
Key points
- Both an iDeCo lump sum and a retirement allowance use the retirement-income deduction.
- Their service/contribution periods can overlap, limiting the combined deduction.
- Payout order and the gap between them affect the result.
- Model the sequencing before you elect a payout method.
Why timing matters
The retirement-income deduction is based on years of service (or iDeCo contribution years). When you receive two lump sums — a company retirement allowance and an iDeCo payout — the rules can treat their periods as overlapping, so you do not simply add two full deductions. Receiving them in a particular order, or with enough years between them, can preserve more deduction.
Model it first
The interaction is intricate and depends on your service years, contribution years, and the amounts involved, plus whether you take iDeCo as a lump sum or as a pension. Before you fix a retirement date or elect a payout method, model the alternatives — this is a common area to consult a professional so a favorable deduction is not accidentally lost.
Who this is for
- People near retirement with iDeCo and a pension
- DC-plan members planning payout
What this is not
- People with only one retirement payment
- Wrong sequencing can waste the retirement-income deduction — model before you commit.
Frequently asked questions
Do I need to file a tax return in Japan?
Many employees do not, because tax is settled by year-end adjustment (年末調整). You generally must file (確定申告) if you have side income over ¥200,000, two or more employers, self-employment income, sizeable investment or crypto gains, or you want to claim deductions like large medical costs or a first-year mortgage credit. Filing season is Feb 16 – Mar 15 via e-Tax. When unsure, check the NTA guidance or ask a 税理士.