Time enrolled in National Pension is not always the same as time counted for a lump-sum withdrawal. This matters if you had student payment deferrals, full exemptions or partial exemptions. Before entering a number into a calculator, identify the recorded payment status of each month and distinguish the withdrawal calculation from future old-age pension qualification.
Sort months by payment status
Under the Japan Pension Service withdrawal rules, the National Pension six-month test uses a weighted total: fully paid months count as one; months with one-quarter, one-half or three-quarters of the premium exempted count as 0.75, 0.5 or 0.25 respectively, when the required remaining premium was paid. Unpaid months do not count. Full exemption and unpaid student-deferral periods do not add paid-equivalent months to this calculation.
Write both the exemption fraction and the paid fraction on your worksheet. "Three-quarters exempt" means the paid fraction is one-quarter, not three-quarters. This small wording difference can change the result substantially when several months are involved.
Try a weighted-month example
Assume a hypothetical record contains four fully paid months and four half-exempt months for which the remaining premiums were paid. The weighted total is 4 + (4 × 0.5) = 6 months. It is neither four months nor eight fully paid months.
In a second example, four fully paid months plus four three-quarters-exempt months produce 4 + (4 × 0.25) = 5 months. Eight calendar months of enrollment would therefore not satisfy the six-month paid-equivalent test in that example. Other eligibility requirements must still be checked even when the arithmetic reaches six.
Understand what a student deferral does
The student special payment system is an application-based deferral, not proof that premiums were paid. Approved periods can count toward old-age pension qualification, but do not increase the old-age basic pension amount unless the premiums are subsequently paid under the applicable rules.
Keep the approval notice and check the actual record. Do not classify a month as approved solely because you were attending university, or classify an approved month as an ordinary unpaid month just because no money left your bank account. Different statuses can have different implications outside the withdrawal calculation.
Separate National Pension from Employees’ Pension
The official withdrawal rules above apply a separate six-month insured-period requirement to Employees’ Pension. Do not combine, for example, three National Pension months and three Employees’ Pension months and assume that either scheme’s withdrawal threshold has been met.
For a mixed history, prepare separate scheme totals and ask Japan Pension Service how your actual record is assessed. Also review eligibility for a future pension before deciding on a withdrawal. Counting months for an immediate payment is only one part of that decision.
Prepare a record-based question
For each uncertain period, record its dates, status shown, exemption approval if any and payment evidence. A useful inquiry is: "These months show partial exemption; has the required remaining payment been recorded, and what weighted total applies?"
Do not make an extra payment solely on the assumption that it will generate a larger refund. Ask about payment eligibility, treatment and the effect on preserved pension rights first. Our complete withdrawal guide provides the broader application context. Use the pension withdrawal calculator only after you know which scheme and month count your inputs represent.