THE REAL RETURN ON DELAYING SOCIAL SECURITY

EVERY FEW MONTHS, I come across yet another article claiming that delaying Social Security is like earning an 8% guaranteed return. It’s a comforting phrase—clean, simple, and easy to repeat. Unfortunately, it isn’t true.

Yes, the Social Security Administration awards an 8% delayed retirement credit for each year you postpone benefits beyond full retirement age. But that 8% is simple interest, not compound. And no matter how attractive the credit looks on the surface, it ignores an uncomfortable fact: You’re giving up three full years of monthly checks to earn it.

When we account for the actual cash flows—what we give up and what we get back—the real return looks very different.

A REAL-WORLD EXAMPLE

Take someone born in 1960 or later. Their full retirement age is 67. If they delay benefits to age 70, here’s what happens:

• They skip 36 monthly payments.
• They earn 24% more in monthly benefits for the rest of their life.

Suppose the age-67 benefit is $1,000 a month. Delaying means turning down $36,000 over three years (36 × $1,000). At age 70, the monthly benefit jumps to $1,240—a $240 increase.

So what’s the rate of return on the $36,000 “investment” needed to earn an extra $240 a month for life?

This is where the math tells a much quieter story than the 8% billboard slogan.

THE TRUE RATE OF RETURN

Using a basic internal rate of return (IRR) calculation—treating the skipped payments as an upfront cost and the extra income as a lifetime annuity—the result comes out to:

Approximately 5.3% to 5.5% per year, inflation-adjusted.

That’s the conclusion reached by:

• The Social Security Administration (~5.3%)
• Mike Piper’s Open Social Security calculator (~5.25%)
• Research from Kitces, Wade Pfau, and Bogleheads contributors (5.0%–5.6%)
• My own spreadsheet calculation (5.48%)

Why isn’t it 8%?

Because:

1. The 8% credit is simple, not compound.
2. You give up three years of payments upfront.
3. The boosted benefit doesn’t start until age 70.
4. Mortality matters—you might not live long enough to enjoy the higher payments.

Add these factors together and the real return shrinks by roughly 2.5 to 3 percentage points.

Still good? Yes. But not magical.

THE BREAK-EVEN AGE

Another way to look at the decision: When do you come out ahead?

• If you live past 83 or 84, delaying benefits to 70 produces more total dollars.
• If you die before 83, claiming at 67 would have put more money in your pocket.

Those ages assume today’s average life expectancy—about 84 for men and 87 for women once you’ve already reached 67.

In other words, for someone in average or better health, delaying remains a solid deal. But the real advantage depends on living long enough to enjoy it.

WHAT THIS MEANS FOR RETIREES

The truth sits somewhere between the headlines:

• No, delaying doesn’t earn 8%.
• The real return—roughly 5.3%—is still quite respectable, especially in a world where “risk-free” real returns hover close to zero.

The decision to delay should still factor in health, longevity expectations, cash-flow needs, spousal benefits, and tax planning. But at least the math is clear: the famous 8% credit overstates the true economic return by a meaningful margin.

BOTTOM LINE

Delaying Social Security from 67 to 70 offers a real return closer to 5.3%, not 8%. That’s still a strong, inflation-adjusted, government-backed payout—but it isn’t the free lunch it’s often advertised to be.

Like most things in retirement planning, the best decision depends less on slogans and more on understanding the numbers.

Note: AI helped me with the math.