Why Withdrawal Rates And Spending Rates Differ

A retiree who withdraws a given sum from a portfolio rarely gets to spend all of it. The gap between what leaves the account and what reaches the household is structural rather than accidental.

The two numbers measure different things

A withdrawal rate describes the fraction of a portfolio removed in a year. It is a statement about the portfolio's depletion, measured at the account boundary rather than at the till.

A spending rate describes what the household actually consumes. The two coincide only in the rare case where every pound withdrawn is available to spend without deduction.

Confusing them makes a plan look more or less sustainable than it is. A spending figure quoted as a withdrawal figure understates the drain on the portfolio.

Tax and fees sit between the two

Withdrawals from tax-deferred accounts are generally treated as income in the year they are taken, so part of the sum is committed before it is available. The exact treatment varies by jurisdiction and changes over time.

Investment costs work similarly but quietly. Platform charges and fund expenses are usually taken from the assets themselves, so they reduce the balance without ever appearing as a withdrawal.

The result is that two retirees with identical spending can have materially different withdrawal rates, purely because of where their money is held and what it costs to hold.

Lumpy costs distort a single year's figure

Retirement spending is not smooth. A roof replacement, a car, or a large family expense can push one year's withdrawal well above the long-run average.

Measuring a withdrawal rate from a single year of that kind produces an alarming number that describes nothing durable. Smoothing across several years gives a figure that can actually be compared.

Plans that ignore lumpiness tend to build reserves too small for it, which forces the retiree to sell assets at whatever price the market happens to be offering.

Why the gap widens with tax-deferred balances

The larger the share of wealth sitting in accounts whose withdrawals are taxable, the more must be withdrawn to fund a given level of spending. The portfolio does more work for the same result.

Households with a mix of taxable, tax-deferred and tax-free accounts can vary the mix in any given year, which changes the relationship between the two rates from year to year.

This is a mechanical relationship, not a judgement about which accounts are preferable. It simply means the two figures cannot be read interchangeably.

How the difference shows up in planning

A plan built on spending needs converting into withdrawals before it can be tested against a portfolio, and the conversion depends on the account mix and the applicable rules.

Where that conversion is skipped, projections tend to run optimistic, because the portfolio is credited with funding costs it never actually covered.

Stating explicitly which of the two figures a plan is quoting removes most of the ambiguity, and makes two plans comparable to each other.