The national pension is not set by what you have paid so far — filling months through back-payment and voluntary enrollment
Two colleagues on the same pay at the same company receive different pensions at 65: ₩693,673 and ₩860,124 a month in today's money. A ₩170,000 difference for life. What differed was 20 years versus 25 years of coverage, and those five years were military service and pre-employment gaps filled later by back-payment. The pension does not end with what you have paid. Its size depends less on the amount than on the number of months, and there are two doors: back-payment to fill empty months, and voluntary enrollment for those without income.
Conditions used in the calculation
- Case
- born 1985 · income ₩3M · joined 2010 · 20 vs 25 years · age 65 · today's money
- Step ①
- the formula set by months: two numbers (average income of all and of you · coverage period) · under 10 years no pension · 10 years half · +5% a year to 20 · +5% a year beyond
- Step ②
- back-payment: exemption, exclusion and military service periods · fillable periods under 10 years · the contribution in the month of application × months · based on current income · installments carry interest
- Step ③
- voluntary enrollment: homemakers, students, retirees · apply to the Service from 18 until 60 · after 60, continued enrollment to 65
- Step ④
- value: how much five years adds · the longer you live · may be partly reduced if you have income
- Where to check
- National Pension Service website (coverage period · exemption periods · projected pension)
Results
- 20 vs 25 years (back-payment)
- ₩693,673 → ₩860,124 · ₩166,451 for life
- By coverage period
- 10 years ₩361,933 · 15 ₩528,384 · 20 ₩693,673 · 25 ₩860,124 · 30 ₩1,026,574, a little over ₩160,000 per five years
- ₩160,000 × 20 years
- nearly ₩40M in today's money
- Five years of back-payment (at ₩3M)
- ₩285,000 a month · ₩17.1M for five years
- The 10-year threshold
- below it no pension · lump sum
- The ₩170,000 in the opening
- same company, same pay · the difference was the filled months
At a glance
From ₩361,933 at 10 years to ₩1,026,574 at 30, rising a little over ₩160,000 per five years.
- 10 years₩361,933
- 15 years₩528,384
- 20 years₩693,673
- 25 years₩860,124
- 30 years₩1,026,574
Why it works this way
Two colleagues on the same pay at the same company receive different national pensions at 65. One gets ₩693,673 a month in today's money, the other ₩860,124. A ₩170,000 difference for life. The contribution rate and income were the same; what differed was the coverage period, 20 years versus 25. Those five years were not more years at the company but military service and pre-employment gaps filled later by back-payment. The pension does not end with what you have paid. There is back-payment to fill empty months and voluntary enrollment for those without income, and most people leave the gaps not knowing these two doors exist. It is commonly assumed the company's contributions are the end of it, but there are two doors you open yourself.
National Pension Act Articles 51 and 63.
- Two numbersaverage income (everyone + you) · coverage period · under 10 years: no pension · lump sum
- Steps10 years: half the basic amount · +5% a year to 20 · full at 20 · +5% a year beyond
- ₩3M · joined 201010 years ₩361,933 · 15 ₩528,384 · 20 ₩693,673 · 30 ₩1,026,574, a little over ₩160,000 per five years
At the same income, the number of months almost entirely decides it, which confuses people. Not knowing, you take a lump sum near 10 years and lose a lifelong stream.
Step ② Back-payment is the door that fills empty months from behind, and the five years in the opening come from here. Exemption, exclusion and military service periods can be filled, and the fillable period is under 10 years. The back-payment contribution is the contribution in the month of application × months, based on current income, paid at once or in installments with interest. Back-paying from 20 to 25 years raises ₩693,673 to ₩860,124, ₩166,451 for life. Only gaps after the first payment count, with military service as the exception, which confuses people; not knowing, you leave five fillable years and receive ₩160,000 less every month for life.
National Pension Act Articles 10 and 13.
- Whothose not otherwise covered (homemakers · students · retirees) · apply to the Service from 18 until 60 · contributions based on an income you choose · floor by decree · withdrawal by application
- Valuestacks months · reaching 10 years enters the formula · back-payment can be applied for during voluntary enrollment
- After 60continued enrollment to 65, the path over the threshold for those short of 10 years
Even with a spouse in workplace coverage, your pension is your own, which confuses people. Not knowing, you never clear 10 years and two people live on one pension.
Step ④ The value. 10 years ₩360,000, 15 years ₩520,000, 20 years ₩690,000, 25 years ₩860,000, 30 years ₩1,020,000, a little over ₩160,000 per five years, and ₩160,000 × 20 years is nearly ₩40M in today's money. Five years of back-payment at ₩3M is ₩285,000 a month, ₩17.1M in total, so what you receive usually exceeds what you pay. Two conditions: the longer you live the more it is, and income may reduce it in part. Back-payment is cheaper the earlier you do it, which confuses people; not knowing, you buy the same months at a higher price after your income rises. The checklist is three lines: ① coverage period, exemption periods and projected pension on the Service website; ② whether the empty months qualify for back-payment and how many months of military service; ③ the added pension versus the contributions to pay. With three lines, pension preparation is done, and a spouse without income writes the same three lines in their own name.
All four steps are passed: the number of months, back-payment, voluntary enrollment, five years = ₩160,000 a month. The two colleagues' ₩170,000 was the filled months. Not knowing the 10-year threshold loses a lifelong stream, not knowing back-payment loses ₩160,000 a month, not knowing voluntary enrollment leaves one pension. Two things to do now: check the coverage and exemption periods on the Service website, and compare the back-payment for empty months with the added pension, looking at voluntary enrollment for a spouse. Today's-money conversion, reductions and installment interest can be checked at a Service branch. The pension does not end with what you have paid.
The legal basis
Drawn from government announcements and the statutes themselves as primary sources, covering only the relevant part.
National Pension Act Articles 51 and 63 (Basic pension amount · Old-age pension amount)
In force Current (checked 2026-09-05)
The basic pension amount reflects the average income of all members (A) and of the member (B) together with the coverage period. Ten years or more of coverage is required for an old-age pension. Adjusted 5% per year from a 20-year base.
What this means
At the same income the number of months almost entirely decides it. Ten years is the threshold and each five years adds a little over ₩160,000.
National Pension Act Article 92 (Back-payment of contributions)
In force Current (checked 2026-09-05)
Exemption, exclusion and military service periods may be back-paid based on the contribution at the time of application. Eligible periods are under 10 years. Interest applies to installments.
What this means
Empty months are filled from behind. Based on current income, so cheaper the earlier it is done.
National Pension Act Articles 10 and 13 (Voluntary enrollment · Continued enrollment)
In force Current (checked 2026-09-05)
A person aged 18 to under 60 who is not a workplace or regional member may enroll voluntarily by applying to the Service. A member who reaches 60 may continue enrollment to 65.
What this means
A door that stacks months without income. If short of 10 years, keep paying to 65.
National Pension Act Article 63-2 (Old-age pension while earning income)
In force Current (checked 2026-09-05)
Where a recipient of an old-age pension engages in income-earning work, part of the pension is reduced for a set period.
What this means
Working while receiving it may reduce it in part. A stated condition, not part of the calculation.
Run it on your own numbers
The calculator opens with these conditions already filled in. Change the figures and your own case comes straight out.
Open the National Pension Estimator
Frequently asked
Can any period be back-paid?
No. Exemption and exclusion periods after the first contribution and military service periods qualify, and the fillable period is under 10 years. Only gaps after the first payment count, with military service as the exception.
How much is back-payment?
The contribution in the month of application × months, based on current income. At ₩3M income that is ₩285,000 a month, ₩17.1M for five years. Installments carry interest, and it is cheaper the earlier you do it.
How much does five years of back-payment add?
At ₩3M income, 20 years at ₩693,673 becomes 25 years at ₩860,124, ₩166,451 more for life. Over 20 years that is nearly ₩40M in today's money.
Can a homemaker join the national pension?
Yes, by voluntary enrollment, applying to the Service from 18 until 60. Even with a spouse in workplace coverage your pension is your own, and reaching 10 years enters the formula.
I am 60 and short of 10 years.
Continued enrollment lets you keep contributing to 65. It is the path over the threshold for those short of 10 years.
Is the pension reduced if I work while receiving it?
If income exceeds a threshold, part may be reduced. Check the reduction rules and today's-money conversion at a Service branch.
Results are estimates based on the inputs and on the rules as at the stated date. They may differ from a lender's actual assessment, and the rules change often. Take professional advice before any decision that matters.