50岁起开始的资产积累与免税投资制度的运用策略｜从iDeCo和NISA的特点到产品选择，再到10年定投模拟，全面涵盖

1. 基于生活方式倒推的资产配置

在开始进行资产配置时，最关键的一点是明确决定“自己希望实现怎样的生活方式”。
特别是如果目的是为退休生活做准备，就需要按照以下顺序分阶段进行思考：将来将采取何种工作方式、能领取多少公共养老金，以及如果仅靠公共养老金无法覆盖生活费，具体需要准备多少资金。
这正是所谓的“从目标倒推来规划资产配置”的方法。
在此基础上，在实际进行投资时，将按照“使用何种免税制度”以及“投资何种金融产品”的顺序，制定具体的计划。

本文将针对主要的免税投资制度——确定缴费型养老金（DC）和少额投资免税制度（NISA）——进行概述，并讲解金融产品的选择方法、全面的资产配置模拟，以及针对不同年龄段的投资策略。

2. 免税投资制度的概要与特点

一般而言，公司职员可利用的代表性免税制度主要有确定缴费型养老金（DC）和少额投资免税制度（NISA）这两项。
通常情况下，投资所获得的收益需缴纳20.315%的转让所得税，但若利用这些制度，投资收益即可免税。
不过，DC与NISA在制度设计上存在显著差异。

DC与NISA的最大差异及适用场景

最大的差异源于DC属于“养老金制度”。
正因DC是养老金制度，因此享有针对缴费金额可享受所得扣除的强力税收优惠措施（此外，企业型DC的缴费金额也不计入社会保险费的计算范围）。
另一方面，该制度原则上设有60岁前不得提取的限制。
相比之下，NISA虽需从缴纳所得税及社会保险费后的“实际到手金额”中进行投资，但具备随时可出售变现的高流动性（优势）。
虽然这两项制度存在显著差异，但在难以抉择时，根据“目的”进行选择是基本原则。

• 为晚年生活储备资金
  优先利用设有取款限制的DC
• 为应对人生中出现的各种重大事件（子女教育费、购房费、装修费、护理费等）而筹集资金
  利用可随时取款的NISA

以本次案例中提到的A先生为例，由于其明确的目标是为晚年生活储备资金，因此建议首先考虑利用企业型DC或个人型确定缴费养老金（iDeCo）。

iDeCo与NISA的比较

iDeCo（个人型确定缴费养老金）

• 参保资格
  国民年金参保人（※另有参保资格类别、缴费上限等其他参保条件）
• 参保期间
  20岁以上且未满65岁
• 开始领取
  60岁至75岁
• 税收优惠
  缴费时，保费可全额抵扣应纳税所得额
  投资期间，投资收益免税
• 领取时，适用公共养老金等扣除／退休所得扣除
  • 缴费时，保费可全额抵扣应纳税所得额
  • 投资期间，投资收益免税
  • 领取时，适用公共养老金等扣除／退休所得扣除
• 投资对象
  本金保障型产品（定期存款、保险产品等）、投资基金
• 年度投资（缴费）上限
  每月20,000日元～68,000日元（※上限金额因公共养老金的参保类别及所在企业养老金制度的参保情况而异）

NISA（小额投资免税制度）

• 参保资格
  年满18周岁（以1月1日为准）
• 参保期限及开始领取
  无期限限制
• 税收优惠
  仅在投资期间的投资收益免税（缴款时及领取时无税收优惠）
• 投资对象
  • [Regular Savings Investment Category] Mutual funds that meet the criteria specified by the Financial Services Agency
  • [Growth Investment Category] Listed stocks, mutual funds, etc. (*Excluding stocks subject to delisting or special supervision, mutual funds with a term of less than 20 years, monthly distribution-type mutual funds, and certain mutual funds that use derivative transactions)
• Annual Investment Limits
  Regular Savings Investment Category: 1.2 million yen per year / Growth Investment Category: 2.4 million yen per year
• Lifetime Investment Limit
  18 million yen (of which 12 million yen is allocated to the Growth Investment Category)

3. How to Choose Mutual Funds

Once you’ve decided which program to use (iDeCo or NISA), the next step is to select the actual investment products.
Understanding the perspective from which mutual fund developers create their products can help guide your selection.

Product Development Perspectives and Personas (Target Customer Profiles)

When structuring a mutual fund, the first step is to define a “persona” (target customer profile) and anticipate investors’ needs.
The starting point for development is considering whose concerns the mutual fund is designed to address.
From the investor’s perspective, it is crucial to determine whether a mutual fund can effectively address their specific concerns.

Selection of Investment Assets

While mutual funds can invest in a wide variety of assets worldwide, risk and return vary significantly depending on the specific assets chosen.
In addition to stocks, bonds, and real estate investment trusts (REITs), there are indications that commodities and, in the future, cryptocurrencies may also be included in mutual fund portfolios.
Therefore, it is essential to choose a mutual fund that includes investment assets you can understand.

Choosing an Investment Strategy (Active vs. Passive Management)

There is a key decision point: whether to choose “active management” or “passive management (index investing).”
Your approach to risk varies significantly depending on which strategy you choose.
Even within passive management, risk and return characteristics vary depending on the benchmark (index).
For example, passive management of small- and mid-cap stocks may actually carry less risk than active management of large-cap stocks.
If you choose active management, be sure to verify whether the fund has a track record of outperforming its benchmark over the long term.

Checking the Investment Trust Structure and Costs

It is also necessary to review the structure of the investment trust.
In particular, “fund of funds” structures that include foreign investment trusts tend to have higher costs (such as management fees).
Taking currency-selection funds—which have become popular among younger generations—as an example, these involve custodian fees (charged by the custodian bank) as part of a minimum guarantee system for foreign investment trusts, making them investment trusts with effectively high costs.

The Importance of Distribution Policies

Distribution policies are also extremely important.
Since asset management companies have fixed sources of funds available for actual distributions and each company has its own internal rules, caution is required when purchasing distribution-type mutual funds.
However, in retirement asset management, receiving distributions has the same effect as drawing down assets, so distribution-type mutual funds may also be a viable option.

Asset Accumulation for Retirement and Specific Product Selection for Mr. A

Given these considerations, balanced mutual funds emerge as a strong candidate for Mr. A’s specific product selection for asset accumulation during retirement.
A specific example of a balanced fund is the “Tawara No-Load Balance (8-Asset Equal-Weight Type)” managed by Asset Management One.
Thanks in part to favorable market conditions, this fund has achieved a total return of +90.9% from July 28, 2017 (the fund’s inception date) through December 30, 2025, which translates to an annualized return of approximately 8% to 9%.
For beginners in particular, the approach of entrusting a balanced fund to a fund manager is effective.
For asset management starting in one’s 50s, it is advisable to make a balanced fund the core of your portfolio.
There are various other combinations of balanced mutual funds available.
In addition to the “4-Asset Equal-Weight Balance” strategy adopted by the Government Pension Investment Fund (GPIF)—which allocates 25% each to domestic equities, foreign equities, domestic bonds, and foreign bonds—there are also “6-Asset Equal-Weight Balance” and “8-Asset Equal-Weight Balance” strategies that add domestic REITs and foreign REITs to these categories.
Incidentally, the GPIF’s basic portfolio has delivered an annualized return of +4.51% from fiscal year 2001 through the second quarter of fiscal year 2025 (end of September 2025).
This can be considered a sufficient return in terms of protecting assets from inflation.

4. Investment Simulation for Those in Their 50s

We will examine the question, “What would the investment results be if one started investing in their 50s?” using specific figures.
As a premise, we assume that a balanced fund was used and achieved an annual return of 4%.

In addition, starting in 2027, the monthly contribution limit for iDeCo for salaried employees is scheduled to increase from 16,000 yen to 20,000 yen. Therefore, let’s consider a scenario where a person contributes 60,000 yen per month for 10 years, from age 54 to 64.
The specific progression of the assets can be divided into the following three periods:

① Accumulation Period (10 years from age 54 to 64)

If you invest 60,000 yen per month for 10 years at an annual return of 4%, the total investment amount (cumulative investment) will be 7.2 million yen.
However, with the addition of a 4% annual return, the end-of-month asset value at the end of the 10-year accumulation period (at age 65) will reach approximately 8.83 million yen.

② Accumulation Halt and Investment Continuation Period (10 years from age 65 to 74)

After age 65, no new investments are made; instead, the approximately 8.83 million yen on hand continues to be invested at an annual rate of 4%.
After this 10-year period of “continuing only the investment,” the end-of-month asset value at the end of age 74 (at age 75) will grow to approximately 13.07 million yen.

③ Withdrawal Period (20 years from age 75 onward)

The approximately 13.07 million yen accumulated by age 75 will be withdrawn in fixed monthly amounts over the next 20 years, from age 75 to 94, while continuing to be invested at an annual rate of 4% (fixed monthly withdrawals).
According to this simulation, it will be possible to withdraw approximately 79,000 yen per month for living expenses.

Summary and Benefits of the Simulation

By supplementing your living expenses with 79,000 yen per month over 20 years, the total amount received will reach approximately 19 million yen.
This demonstrates a significant return on the initial total investment of 7.2 million yen.
Even if you start in your 50s, rather than stopping your investments completely at age 65, you can create significant financial flexibility for your retirement by continuing to invest until age 75 and then making partial withdrawals while continuing to invest.
Furthermore, since salaries generally peak in one’s 50s, it makes sense from the perspective of maximizing the tax benefits of defined contribution (DC) plans, such as the income tax deduction for contributions.

5. Asset Accumulation Strategies and Generational Perspectives

As a basic approach to securing funds for retirement, the standard strategy is to focus the “core” portion of a core-satellite strategy on globally diversified investments—such as global equity funds that invest in a mix of global stocks and bonds—and to make regular, long-term contributions.
However, the appropriate systems and approaches vary depending on age group, family structure, and employment status.
The examples and approaches by age group outlined in the materials are as follows.

Case of a Stay-at-Home Spouse (Mr./Ms. B in the materials)

Because they have no or only limited earned income, they cannot take advantage of the tax benefit known as the “full income tax deduction for contributions,” which is the greatest benefit of the DC plan.
Consequently, while they may have previously relied solely on NISA to invest in funds focused on stocks and other assets, the recommended approach going forward is to adopt a hybrid strategy by adding DC balanced funds to their portfolio.

Case of the Younger Generation Entering the Workforce (Eldest Daughter, Ms. C)

As a first step, it is recommended to start regular savings investments by utilizing the “regular savings investment limit” under NISA, which is an easy way to get started.
Since the younger generation has a very long investment horizon during which they can pursue returns, the standard approach is to continue investing in high-growth products, such as global equity funds, to maximize the benefits of compound interest.
After that, depending on eligibility for employer-sponsored DC plans or iDeCo, it is wise to divide regular investments between the two systems: NISA and DC.

Case of a Student (Eldest Son, Mr. D)

Even for university students, unless they are enrolled in a government-funded program (such as the Special Exemption System for Student National Pension Premiums), using a portion of their part-time income to start regular investments through NISA early on is an effective option for building future assets.

Conclusion: The Mindset for Long-Term Investing

The essentials of asset building can be summarized in the following three points.

1. Start making regular investments as soon as possible using tax-exempt programs (DC and NISA)
2. Choose your investment amounts and targets wisely
3. Continue investing over the long term while managing risk so that you can maintain your current lifestyle even if there is a market crash on the scale of the Lehman Shock

During historic financial crises or periods of sharp market declines, psychological anxiety can make you feel tempted to stop investing. However, continuing to make regular contributions without panicking is an absolute prerequisite for reaping the long-term benefits of compound interest.

Furthermore, by starting your regular investments as early as possible, you can ensure a longer investment horizon, which in turn allows the power of compound interest to work more effectively.

As you continue your regular investments over 20 or 30 years, you will inevitably experience significant market downturns on numerous occasions.

However, by cultivating financial literacy through these experiences, you can build a solid foundation of wealth that remains unshaken by market fluctuations.