Guaranteed Income

Step 1: Start With Total Desired Retirement Spending

First estimate your total annual retirement spending need, including:

  • housing

  • food

  • healthcare

  • travel

  • taxes (property, income ~20%)

  • insurance

  • hobbies/gifts

  • inflation cushion

Example: Annual Amount

  • Living expenses @ $120,000

  • Taxes @ $20,000

Total required cash flow @ $140,000

Step 2: Subtract Guaranteed Income Sources

Then subtract:

  • Social Security

  • pensions

  • annuities

  • other reliable income streams

because those reduce what your investment portfolio must provide.

Example:

Guaranteed Income / Annual Amount

Social Security

$45,000

Pension

$25,000

Total guaranteed income

$70,000

So now:

140,000 - 70,000 = 70,000

Your portfolio only needs to generate:

  • about $70,000/year

Step 3: Apply the 4% Rule

Then:

70,000 x 25 = 1,750,000

Estimated required portfolio:

  • about $1.75 million

instead of:

  • $3.5 million without guaranteed income.

That is exactly how most professional retirement planning models use pensions and Social Security.

The Important Tax Question:

Use Guaranteed Income AFTER Taxes or BEFORE Taxes?

The cleanest professional answer is:

Everything should be converted into NET spendable cash flow

Meaning:

  • your spending target should reflect actual spending needs

  • your guaranteed income should reflect what is available after taxes

  • your portfolio withdrawals should also account for taxes

Practical Planning Framework

Best Practice:

Use AFTER-tax cash flow for all comparisons.

Example:

  • Gross- Taxes = Net Spendable

Social Security: (assuming 10% tax)

  • $50,000 - $5,000 = $45,000

Pension: (assuming 20% tax)

  • $40,000 - $8,000 = $32,000

Net guaranteed income

$77,000

If your desired retirement lifestyle costs:

  • $150,000 AFTER tax

then investments need to provide:

150,000 - 77,000 = 73,000

Then:

$73,000 x 25 = $1,825,000

Why Gross Numbers Can Mislead

Suppose:

  • pension = $50,000 gross

  • but after tax only $38,000 is spendable

If you subtract the full $50,000 from your spending needs, you may:

  • underestimate required assets

  • withdraw too aggressively later

This becomes especially important when:

  • most assets are in traditional IRAs/401(k)s

  • RMDs begin

  • pension income is large

  • state taxes apply

  • Medicare IRMAA surcharges occur

Professional Retirement Planning Usually Uses:

“After-Tax Income Replacement”

Professional retirement software often models:

  • after-tax retirement spending
    vs.

  • after-tax retirement income

because retirees spend net dollars, not gross dollars.

One More Important Nuance:

Social Security Is Only Partially Taxable

Unlike pensions or IRA withdrawals:

  • Social Security often has favorable taxation

  • sometimes 0%

  • sometimes up to 85% taxable

So:

  • $50,000 Social Security may behave very differently from

  • $50,000 IRA withdrawal

This is why tax-aware withdrawal sequencing matters greatly.

The Simplified Formula

A more realistic version of the 4% rule becomes:

Required Portfolio ≈ [(after-tax annual spend)-(after-tax guaranteed income)] / 0.04

or equivalently: (Net Spending Gap) x 25

[160.77:73x25:1825]

Final Planning Perspective

The 4% rule works best when you think of it as:

“How much investment portfolio is needed to fill the gap?”

not:

  • total retirement income
    but:

  • the portion NOT already covered by guaranteed income.

For many retirees:

  • Social Security dramatically lowers required assets

  • pensions can reduce sequence-of-return risk

  • guaranteed income allows higher equity allocations or safer withdrawals

This is one reason why two retirees with identical lifestyles may need radically different portfolio sizes depending on:

  • pension strength

  • Social Security timing

  • tax structure

  • housing status

  • healthcare coverage.

Michael Wei