The Better Measure for Managing Retirement Spending (Including Big Purchases)

Retirement
planning is often dominated by withdrawal rules, Monte Carlo
probabilities, and portfolio‑centric heuristics. But none of these tools
directly measure the core financial question every retired household
faces: Can my assets support the lifetime spending I want—including
the occasional big purchase—without jeopardizing long‑term solvency?The actuarial answer is funded status.Funded status compares the present value of what you have to the present value of what you plan to spend.
It is the same solvency metric used by pensions, endowments, and
insurers. When applied to households, it becomes a powerful, intuitive
tool for managing both ongoing spending and significant one‑time
decisions.Why funded status is superior to withdrawal‑rate rulesWithdrawal
rules treat retirement as a static math problem. Funded status treats
it as a long‑term liability management exercise.A funded status above 100% means your assets can support your lifetime spending plan at today’s discount rates.A funded status below 100% means the plan is underfunded and requires adjustment.A funded status well above 120% indicates surplus capacity and flexibility.This
single number captures the entire retirement plan—timing of Social
Security, longevity horizon, spending shape, discount rates, and market
conditions. It is the closest thing retirees have to a solvency
dashboard.The missing piece in most retirement planning: non‑linear purchasesMost
retirees don’t just spend smoothly. They buy cars. They remodel
kitchens. They help adult children. They take major trips. They may even
consider relocating.These decisions are non‑linear—large,
lumpy, and often emotionally driven. Traditional withdrawal rules offer
no guidance on whether such purchases are affordable. Monte Carlo
simulations can show probability impacts, but they rarely translate into
a clear “yes, no, or how much.”Funded status does.Because funded status is a ratio of assets to liabilities, you can simply:Compute funded status today.Subtract the cost of the proposed purchase from assets.Recompute funded status.Evaluate the change.Note
that sometimes this calculation can be a little more complicated if the
purchase is also expected to affect future cash flows. See our post of July 17, 2025 for the process under these conditions. If
funded status remains comfortably above 100% (or above your chosen
threshold), the purchase is actuarially affordable. If it drops below
your sustainability boundary, the purchase compromises long‑term
solvency.This is exactly how institutional plans evaluate discretionary spending. Households can use the same method.Kitces.com’s perspective reinforces this actuarial approachThe June 7/8 2025 Kitces.com Weekend Reading post made this point clearly:“In
sum, financial advisors have more than one tool in their toolbelt when
it comes to analyzing the impact of large purchases by their retired
clients. And while advisors might not consider themselves to be
actuaries, taking an actuarial approach could provide clients with a
metric that allows clients to better understand the impact of potential
purchases on the sustainability of their financial plan!”This
is precisely what funded status provides: a metric that translates a
complex financial decision into a simple, interpretable measure of
sustainability.Funded status creates a dynamic feedback loopRetirement
is not static. Markets move. Rates shift. Spending evolves. A static
withdrawal rule cannot respond to these dynamics. Funded status can.By recalculating funded status periodically retirees gain a disciplined way to adjust spending:When markets rise or discount rates increase, funded status improves → spending can rise safely.When markets fall or discount rates decline, funded status deteriorates → spending should adjust downward.When a large purchase is contemplated, funded status instantly shows whether it is affordable.This is how institutions manage long‑term promises. Retirees deserve the same rigor.The bottom lineRetirement is a multi‑decade liability. It should be managed with tools designed for long‑term solvency. Funded
status is the most accurate, comprehensive, and actionable measure for
guiding retirement spending—including major one‑time purchases.It reframes the central question from “How much can I withdraw?” to:“What spending level—including large purchases—keeps my funded status stable over time?”That is the actuarial approach. And it is the approach that gives retirees clarity, confidence, and control.