The Economics of an Aging World: Who Will Pay for Retirement?

By Bhupendra Thapa

There is a demographic change taking place around the world that may eventually affect government budgets, household savings, labor markets and financial markets more than many of the economic headlines we follow today. People are living longer, while families in many countries are having fewer children. That sounds like good news at first. Longer lives reflect improvements in medicine, nutrition, public health and living standards. Lower fertility can also mean smaller families and, for a period, greater resources available for each child. The economic problem begins when these two trends occur together for a long time. A country eventually has more older people to support and relatively fewer working-age people generating income, paying taxes and contributing to pension systems. This raises a difficult question: who will pay for retirement when there are fewer workers supporting each retiree?

The answer is not simply governments, employers or individuals. The burden will probably be shared, but the balance will differ from country to country. Some governments may increase taxes or contributions, some may raise retirement ages, some may reduce future benefits, while households may need to save more for themselves. At the same time, countries may increasingly depend on immigration, technology and productivity growth to maintain economic output despite slower growth in their working-age populations.

The World Is Getting Older

The demographic shift is already measurable. According to the United Nations World Population Prospects 2024, global life expectancy at birth reached 73.3 years in 2024, more than 8.4 years higher than in 1995. The UN projects global life expectancy to reach about 77.4 years by 2054. This is one of the major achievements of modern economic and social development. People are surviving diseases that once shortened lives, benefiting from better healthcare and living in societies with improved nutrition and sanitation.

At the same time, fertility has fallen dramatically over the long term. The global fertility rate is now close to replacement level and is expected to continue declining. More than half of the world's countries and areas already have fertility below the replacement level of 2.1 births per woman. These changes are not occurring at the same speed everywhere. Some countries still have relatively young populations and comparatively high fertility, while others are already dealing with shrinking working-age populations and rapidly increasing numbers of older citizens.

Putting these trends together produces a major demographic transformation. The United Nations projects that by the late 2070s the number of people aged 65 and above worldwide could reach about 2.2 billion, surpassing the number of children under age 18. That is more than a population statistic. It represents a change in the economic relationship between generations. A larger elderly population means greater demand for pensions, healthcare and long-term care, while countries with fewer young people may have a smaller future workforce available to finance those needs.

Japan Shows What Advanced Aging Looks Like

Japan provides one of the clearest examples of what an advanced aging economy can look like. Japan's official statistics show that 36.24 million people, or 29.3% of its population, were aged 65 or older in 2024. At the same time, Japan's total population fell for the 14th consecutive year. This creates a very different economic environment from a country where the working-age population is still expanding.

Japan has responded in several ways. Older people have remained active in the labor market, companies have adopted more technology and automation, and policymakers have had to consider how economic activity can be maintained with a smaller working-age population. Japan's experience also shows why simply increasing the retirement age cannot solve everything. If people work longer, governments may receive contributions for additional years and pay pensions for fewer years, but older workers still need healthcare and eventually retirement income. The policy also cannot be applied equally to every occupation. Someone working in an office may find it easier to remain employed at 68 than someone whose job requires heavy physical labor.

Japan therefore offers an important lesson. Population aging is not only a pension issue. It becomes a labor-market, productivity, healthcare and economic-growth issue as well.

The United States Faces a Different Kind of Pressure

The United States provides a useful comparison because its demographic structure and retirement system are different from Japan's. Social Security is largely financed on a pay-as-you-go basis. Current payroll taxes help finance benefits for current beneficiaries, while trust fund reserves provide an additional source of financing.

The number of workers supporting beneficiaries has changed substantially over time. In 1950, there were about 16.5 covered workers for every Social Security beneficiary. By 2024, the ratio had fallen to 2.7, and it fell further to approximately 2.6 in 2025.

The latest Social Security Trustees projections show that the ratio will continue to decline as the number of beneficiaries grows faster than the number of covered workers. This is more revealing than simply saying that the United States is running out of money. The deeper problem is demographic. When there were many workers for each beneficiary, relatively fewer workers were required to finance each retiree's benefits. When there are only a few workers for each beneficiary, the same promise becomes more expensive relative to the size of the working population.

The 2026 Social Security Trustees Report projects that the combined OASI and DI trust fund reserves will be depleted in 2034 under its intermediate assumptions. At that point, continuing revenues would be sufficient to pay about 83% of scheduled benefits if no legislative changes are made. This does not mean Social Security suddenly becomes worthless in 2034. It means that the existing financing structure would no longer support the full level of benefits currently scheduled under existing law.

That distinction matters because public discussion can sometimes turn a long-term financing problem into an exaggerated prediction of an immediate collapse. The more useful interpretation is that policymakers have a limited period in which to make changes before the gap becomes much harder to manage.

Japan and America Reveal Two Different Problems

Japan and the United States are therefore facing related but different challenges. Japan already has almost three out of every ten people aged 65 or older, and its total population is declining. The United States has a major pension financing challenge but has a different demographic structure and a much larger population. Immigration can also contribute to population and labor-force growth, providing the United States with an adjustment mechanism that countries with extremely low immigration do not have to the same extent.

The comparison shows why there is no universal solution to population aging. Japan's experience emphasizes the problems created by population decline and labor shortages. The United States demonstrates the financial pressure that can emerge when benefit obligations grow faster than dedicated revenues. Other countries will face different combinations depending on fertility, migration, productivity, pension design, healthcare costs and household savings.

This difference is important for developing economies as well. A country that still has a large young population has an opportunity that an already aged country does not have: time. It can strengthen pension institutions, encourage long-term savings and invest in productivity before demographic pressure becomes severe.

The Retirement Gap Goes Beyond Government Pensions

The retirement problem is also bigger than government pensions. Households need personal savings, employer retirement plans and other assets to maintain their living standards after leaving work. This is where the scale of the challenge becomes difficult to estimate.

The World Economic Forum, using Mercer analysis, estimated in 2017 that the retirement savings gap across eight major economies could reach approximately $400 trillion by 2050. The countries included in that analysis were Australia, Canada, China, India, Japan, the Netherlands, the United Kingdom and the United States.

The $400 trillion figure should not be presented as a current measurement of today's retirement shortfall. It was a long-term projection made in 2017. Nevertheless, it illustrates the scale of the challenge created when expected retirement needs grow faster than available savings.

The important issue is not the exact number itself but the mechanism behind it. If people live longer, they potentially need income for more years. If fertility declines, there may be fewer workers contributing to public systems. If investment returns are weaker than expected, retirement savings accumulate more slowly. If employers increasingly shift retirement responsibility toward individual accounts, households may also carry more investment risk.

Who Will Carry the Burden?

Governments have several choices, although none is painless. Raising the retirement age can reduce the number of years people receive benefits while increasing the period in which they contribute to the economy. However, it can be difficult for workers in physically demanding occupations. Raising taxes or contribution rates can strengthen pension finances, but it places additional pressure on current workers and employers.

Reducing benefits or changing eligibility can improve long-term sustainability but can undermine people's expectations about retirement. Immigration can expand the working-age population, although it is not a complete solution because new workers also require housing, infrastructure, healthcare and employment. Productivity growth can increase the amount of output available to support the population, but productivity improvements take time and are never guaranteed.

The important point is that countries will probably use a combination of these measures rather than rely on one solution. A government that raises the retirement age but does nothing about low productivity may still face economic pressure. Likewise, a country that encourages immigration without investing in housing and infrastructure may simply move the pressure from one part of the economy to another.

Productivity May Become the Most Important Variable

Among these options, productivity may be the most economically interesting. Imagine two economies with the same number of workers and retirees. If workers in one economy produce significantly more output because they have better technology, skills and capital, that economy has more resources available to finance pensions, healthcare and other public services.

This means population aging should not automatically be interpreted as economic decline. A smaller workforce can still support a high standard of living if productivity rises sufficiently.

However, productivity cannot solve the entire problem by itself. Higher productivity may increase national income, but societies still have to decide how that income is distributed. If economic gains are concentrated among a small part of the population, higher productivity may not automatically improve retirement security for ordinary households. Technology can create economic capacity, but policy determines how much of that capacity reaches workers and retirees.

Younger Countries Have an Opportunity

The differences between countries also create an important opportunity for younger economies. Countries that still have relatively young populations have more time to strengthen pension systems, expand financial inclusion, encourage long-term savings and invest in human capital.

They can learn from countries that are already experiencing demographic pressure instead of waiting until the pressure becomes unavoidable. This is particularly important because pension reform becomes much more difficult once a large share of the population is already dependent on retirement benefits.

The demographic transition therefore creates both a challenge and an opportunity. Older economies must manage existing obligations, while younger economies can prepare before those obligations become overwhelming.

What Does This Mean for Younger Workers?

For younger workers, the safest assumption is not that government pensions will disappear or that they will remain exactly as they are today. The more realistic assumption is that retirement systems will change.

Government pensions may remain an important source of income, but personal savings, employer retirement schemes and investments may become increasingly important. Financial literacy therefore becomes more than a personal finance skill. It becomes part of economic resilience.

A worker who understands inflation, compound interest, investment risk, diversification and long-term saving has a greater ability to adapt when retirement conditions change. This does not mean individuals should be expected to solve a structural demographic problem on their own. Pension systems are collective institutions, and governments have a major responsibility to make them financially sustainable. But individuals also need to recognize that relying entirely on one source of retirement income may become increasingly risky.

Author's Analysis: The Retirement Contract Is Changing

What strikes me most about this issue is not the size of the trillion-dollar estimates. It is how quietly the economic relationship between generations is changing. Retirement systems were designed during periods when many countries had relatively high fertility and a growing working-age population. In many places, those conditions no longer exist. The assumptions behind the old retirement contract therefore deserve to be reconsidered.

I do not think this means the world is heading toward a retirement collapse. That would be too simplistic. Economies have repeatedly adapted to major demographic and technological changes. What I do think is changing is the balance of responsibility. Governments may still provide pensions, but taxpayers may have to contribute more. People may work longer. Employers may redesign retirement benefits. Households may need to save more. And economies may have to depend more heavily on productivity growth.

The United States shows that even a large and relatively dynamic economy can face a serious pension financing challenge. Japan shows what happens when demographic aging becomes more advanced and population decline accompanies it. The broader global picture shows that countries are moving through this transition at very different speeds. These differences suggest that the most successful countries will not necessarily be those with the youngest populations, but those that prepare early enough to adapt their economic institutions.

In my view, productivity will eventually matter more than population size alone. A country does not necessarily need a constantly growing population to remain prosperous. It needs sufficient productive capacity to generate the income required to support its population. That makes investment in technology, education, healthcare, infrastructure and human capital extremely important.

But productivity should not become an excuse for ignoring pension reform. Technology can increase output, but it cannot decide how that additional income should be divided between workers, businesses and retirees. That is ultimately a political and social decision. The central challenge is therefore not simply producing more, but creating an economic system capable of sharing enough of that production across generations.

In Conclusion

The aging of the world is not a distant abstraction that begins in 2070. The demographic change is already visible in labor markets, government finances and retirement planning. Yet aging does not produce the same outcome everywhere.

Japan is dealing with population decline and a very high elderly share. The United States is dealing with a major Social Security financing challenge within a different demographic environment. Younger countries still have an opportunity to strengthen savings, pension coverage and productivity before their populations age.

The question, therefore, is not simply who will pay for retirement. A better question is how each generation can produce enough economic value to support longer lives without placing an unreasonable burden on the next generation.

That is the real economic challenge of an aging world.

Sources: 

UN World Population Prospects 2024 (population.un.org), 

UN World Fertility 2024 report, 

Social Security Administration 2025 Trustees Report (ssa.gov), 

American Academy of Actuaries 2025 Trustees Report summary (actuary.org), 

Japan Ministry of Internal Affairs and Communications / Cabinet Office aging reports, 

World Economic Forum "We'll Live to 100, 

How Can We Afford It?" (2017), 

Peterson Foundation (pgpf.org).