I Contributed to Japan's 401(k) for 7 Years Without Once Thinking About How to Cash Out

I’ve been contributing to iDeCo for seven years. Never once thought about how I’d actually get the money out.

Then Japan changed the rules in 2026. I looked into it. And realized my thinking had been embarrassingly shallow.

Quick context for non-Japan readers: iDeCo is Japan’s individual defined contribution pension — think of it as a 401(k) you set up yourself. Your contributions are fully tax-deductible, your investments grow tax-free, and you can’t withdraw until age 60. Sounds great going in. The “going out” part is where it gets complicated.

I Just Wanted Another Tax-Free Box

Back in 2019, Japan’s NISA (the country’s tax-free investment account, closest equivalent to a Roth IRA) had an annual cap of 400,000 yen — about $2,700. Monthly, that’s roughly $220. I had more to invest, but no more tax-free space to put it.

So I opened an iDeCo account. Not for some noble reason like “securing my retirement” or “supplementing my pension.” I just wanted another tax-sheltered box. That’s it.

I set up automatic contributions of 20,000 yen ($130) per month through SBI Securities, the same brokerage where I had my NISA.

One thing surprised me: the fund selection was tiny. The S&P 500 index fund I used in NISA wasn’t available in iDeCo. I ended up picking a Dow Jones index fund instead — same US market exposure, different benchmark. I would’ve preferred S&P 500, but you work with what you’ve got. The fund lineup varies by brokerage and has probably improved since then. But at the time? “Wait, this is all I can choose from?” was my honest reaction.

“You’re the Third Person to Ask”

In Japan, setting up iDeCo requires employer paperwork. There’s a form called the “Employer Registration Application” — a name designed to make you not want to fill it out. When I brought it to HR, I casually asked:

“Does anyone else here have iDeCo?”

“You’re about the third.”

Three people. Out of several hundred employees.

My first reaction was surprise. A system that gives you tens of thousands of yen back every year at tax time, and almost nobody was using it. But that surprise quickly turned into quiet satisfaction. I’m the kind of person who feels good about doing something others haven’t bothered with. A small, irrational win.

The paperwork itself was annoying. But it’s a one-time thing. After that, money gets automatically deducted from your paycheck every month. Set it and forget it. Same principle as index investing — front-load the effort, then let the system run.

And for seven years, that’s exactly what I did. Nothing. No rebalancing, no contribution changes, no fiddling. Much like my first few years of investing, the best strategy was doing absolutely nothing. I couldn’t touch the money even if I wanted to — and I didn’t want to. I thought that was the beauty of iDeCo. Turns out, I was only half right.

The Annual Reward

The single best moment of being an iDeCo holder? Year-end tax adjustment.

20,000 yen per month times 12 months equals 240,000 yen ($1,600) in fully deductible contributions. At my income level, that’s a combined income tax and resident tax rate of about 30%, which works out to roughly 72,000 yen ($480) saved every year.

I’d always assumed it was around $300. When I actually ran the numbers, I was off by a wide margin. The resident tax reduction shows up as smaller paycheck deductions the following year, so it’s easy to miss. I’d been saving more than I realized.

Index investing is mostly boring. Money leaves your account automatically, shares get purchased automatically, and once in a while you glance at the balance and go “huh.” There’s almost no emotional payoff.

That’s why the tax refund matters. Once a year, you get concrete proof that this thing is working. I call it my annual reward. The one moment in index investing that actually makes you feel something. I’ve learned to appreciate it.

And Then I Realized I Had No Exit Plan

For seven years, the only time I seriously thought about iDeCo was when I signed up.

Then in 2026, news broke about the “10-year rule.” I finally sat down and researched how withdrawals actually work.

The verdict? I’d been naive.

Here’s the deal. When you withdraw from iDeCo as a lump sum, Japan applies something called the “retirement income deduction” — a generous tax exemption that shields a large chunk of your payout from taxes. Your company severance pay (yes, most Japanese companies still pay lump-sum severance) gets the same deduction.

The catch: to claim the full deduction on both payouts, you need a gap between them.

Under the old rules, a 5-year gap was enough. Withdraw iDeCo at 60, receive company severance at 65, and both could be fully sheltered. With the right numbers, you’d pay zero tax on either.

Starting in 2026, that gap widened to 10 years.

Withdraw iDeCo at 60? You’d need to wait until 70 for the full severance deduction.

Why the change? Because the 5-year optimization hack went viral. Financial YouTubers and bloggers across Japan were shouting “withdraw iDeCo at 60, wait 5 years, pay zero tax!” The government watched the loophole spread and plugged it. Same pattern as when Japan cracked down on overly generous furusato nozei return gifts. When too many citizens get too clever, the rules change. Worth remembering. Whatever tax optimization works today might not work tomorrow — if it becomes popular enough, the government will close the door. (I wrote about recent tax rule changes in my 2026 tax return breakdown.)

So How Much Tax Are We Actually Talking About?

I ran the numbers for my own situation. My expected company severance is around 10 million yen ($66,000). Yeah, my company isn’t exactly generous with severance. My iDeCo, contributing 20,000 yen per month over 23 years with investment growth, should land around 8 million yen ($53,000).

If I withdraw everything at 60 in one shot, the portion exceeding the retirement income deduction gets taxed. Roughly 350,000 yen ($2,300) in taxes.

If I space the withdrawals 10 years apart, I can use the full deduction twice. Tax bill: zero.

The difference is $2,300.

Side note: starting in 2027, Japan is raising the iDeCo monthly contribution cap to 62,000 yen ($410). I’d been thinking about maxing it out. But at that contribution level, my iDeCo balance could approach 20 million yen ($133,000) — far exceeding the deduction limits. No matter how I time the withdrawals, I’d owe over 1 million yen ($6,600) in taxes. The tax deduction on the way in is real, but the tax on the way out grows too. “Paradise at the entrance, purgatory at the exit” is a bit dramatic, but you get the structure.

So: do I drag this thing out until 70 to save $2,300? Or just pay the tax and be done with it? At some point, this stops being a math problem and becomes a personality question.

Mathematically Optimal, Emotionally Exhausting

The “best” play is clear. Max out iDeCo contributions at the new $410/month cap starting 2027. Funnel the annual tax savings into NISA (Japan’s tax-free account). Space out withdrawals by 10 years. On paper, this extracts every last dollar of value.

But.

Being tethered to a withdrawal schedule until age 70 is exhausting to even think about. I’m a guy who daydreams about early retirement. Having a government pension scheme dictate my financial calendar until 70 feels like the opposite of freedom.

The mathematically optimal answer and the emotionally satisfying answer aren’t always the same.

At 20,000 yen per month, I can structure withdrawals to pay zero tax. Maxing out contributions increases total returns but makes the exit messy. Which is “right” depends on your personality and what role you want iDeCo to play in your life.

If seven years of doing this taught me anything, it’s that the most important thing in investing might be acknowledging how you actually feel. Numbers can be correct and still leave you unsatisfied. If you’re not at peace with the plan, you won’t stick to it.

I Decided iDeCo Is a Retirement Bonus, Not an Investment

After thinking it through, I reframed what iDeCo means to me.

Not an “investment tool.” Not a “pension supplement.” A retirement bonus. A lump sum I’ll receive at 60 on top of my company severance.

Withdraw it all at once. Pay the tax. And instead of feeding the money back into my brokerage account, spend it on something for myself.

Specifically: a round-the-world cruise on the Asuka II with my family. (The Asuka II is Japan’s premier luxury cruise ship — think of it as the Japanese Queen Mary 2.)

Dream big, right? I haven’t actually looked up how much a suite costs. I’m afraid that googling it would crash me back to reality.

Turning iDeCo’s exit into a cruise ticket. Once I made that decision, all the complexity around withdrawal strategies suddenly stopped bothering me.

Can iDeCo Become a Gift to Yourself?

If a coworker asked me “should I start iDeCo?” — here’s what I’d say.

Before you think about strategy, decide what iDeCo means to you.

Can you enjoy the annual tax refund as a small reward? Do you have a picture of what you’ll do with the money at 60? Is this an investment, a retirement fund, or a bonus?

As a system, iDeCo is generous at the entrance and complicated at the exit. But that complexity shrinks to almost nothing once you’ve decided what role it plays.

If locking your money away until 60 sounds like a dealbreaker, iDeCo probably isn’t for you. But if you can picture a life where you genuinely won’t need that money before then, the tax savings are real. (If rising interest rates are reshuffling your financial priorities — mortgage, savings, where to allocate — this piece on the new interest rate environment might be worth a read.) And honestly — if you’re in a position to weigh iDeCo versus NISA in the first place, you’re not living paycheck to paycheck. The odds of truly needing to crack open this account early are lower than you think.

Can iDeCo become a gift to yourself?

That question matters more than whether to start. It took me seven years to figure that out.

I wrote a detailed simulation comparing different iDeCo contribution scenarios on my Note. Check it out if you want the numbers.

Disclaimer: Investing involves risk. This article reflects one person’s experience and is not financial advice.