By Siri · March 2026 · 10 min read
There are hundreds of financial decisions to make in retirement planning. But five of them move the needle more than all the others combined. Most people pull these levers without thinking — and pay for it for decades.
Here are the five decisions, the math behind them, and what the wrong move looks like so you can avoid it.
Stakes: Up to $200,000+ in lifetime income difference
You can claim as early as 62 or as late as 70. The difference is roughly 8% per year. Wait from 62 to 70 and your monthly benefit increases by about 76%. Most people take it early because they need the money or they fear they will die before they break even.
The Math
Break-even between claiming at 62 vs. 70 is typically around age 80-81. A 65-year-old woman today has an average life expectancy of about 86, and a 1-in-3 chance of living past 90. If you live past break-even — which most healthy women do — delaying pays off significantly. If you have other income to bridge the gap, delaying Social Security is often the single highest-ROI decision you can make.
Wrong Move
Taking Social Security at 62 out of anxiety, without actually running the math. Many people leave $150,000-$200,000 in lifetime income on the table.
Right Move
Run your break-even calculation at SSA.gov. If you are in reasonable health and have bridge income, seriously consider delaying to 67 or 70.
Stakes: Healthcare is the single largest retirement wildcard before Medicare
Medicare begins at 65. If you retire before then, you need to bridge your healthcare costs. Options include COBRA (expensive, time-limited), ACA marketplace plans (income-dependent subsidies), a spouse's plan, or part-time work with benefits.
The Math
The enhanced ACA subsidies that reduced premiums for millions of Americans expired at the end of 2025, and 2026 marketplace premiums jumped roughly 18-20%. A 60-year-old woman on an unsubsidized Silver plan can now expect to pay $800-$1,400/month depending on state — that is $9,600-$16,800/year before deductibles and out-of-pocket. If you manage your retirement income below ~$62,000/year, you may qualify for subsidies that bring this down significantly. Over 3 years of early retirement, unsubsidized costs run $29,000-$50,000+.
Wrong Move
Retiring early without a specific, costed healthcare plan. This gap surprises people more than any other.
Right Move
Go to healthcare.gov and model your ACA options based on your projected retirement income. Managing your income below key ACA thresholds can dramatically reduce your premiums.
Stakes: Your allocation in the 5 years before and after retirement matters more than any other 10-year window
Sequence of returns risk is real. A 30% market drop in year 1 of retirement is far more damaging than the same drop in year 10 — because you are withdrawing money while the portfolio is down. The recovery math is brutal.
The Math
A portfolio that drops 30% in year 1 of a 4% withdrawal rate may fail within 20 years, even if the market fully recovers. The same portfolio that drops 30% in year 15 has a much higher chance of surviving. This is why the 5 years on either side of retirement require a different approach.
Wrong Move
Staying 80% equities until the day you retire, then scrambling to shift allocations after a bad year.
Right Move
Begin a gradual allocation shift 3-5 years before your target retirement date. Build a 1-2 year cash cushion so you are not forced to sell equities in a down market.
Stakes: Getting this wrong can cost $50,000-$100,000 in unnecessary taxes over retirement
You have three types of accounts with different tax treatments: pre-tax (traditional 401k/IRA — taxed on withdrawal), Roth (after-tax — grows and withdraws tax-free), and taxable brokerage (capital gains tax applies). The order you draw from them determines your tax bill.
The Math
Many retirees draw down taxable and Roth accounts first, leaving pre-tax accounts to grow — which triggers massive RMDs at 73 (or 75 if you were born in 1960 or later, under SECURE 2.0) that push them into higher brackets. A better strategy often involves Roth conversions between retirement and your RMD start date, when income may be lower.
Wrong Move
Drawing randomly from whatever account has money in it, with no tax strategy. Or leaving pre-tax accounts untouched until RMDs force large taxable withdrawals.
Right Move
Map out your projected income by year from 55-75. Identify the years when Roth conversions make sense. This is one area where a fee-only CPA or fiduciary advisor earns their cost.
Stakes: Working part-time for 2-3 extra years can add 5-10 years of portfolio runway
Full retirement is not the only option. Working 20 hours a week for 2-3 years after your primary career — consulting, fractional work, a passion project — can fundamentally change your retirement math by letting your portfolio grow longer and drawing less from it early.
The Math
If your portfolio needs to last 30 years at $60,000/year, that requires roughly $1.5M. If instead you work part-time for 3 years covering $30,000/year of expenses, you only need $45,000/year from the portfolio for those years, buying 3 more years of compounding. This can add 5-7 years of portfolio longevity.
Wrong Move
Seeing retirement as binary — fully on or fully off. Or staying in a high-stress job longer than necessary when a part-time transition would serve both your finances and your health.
Right Move
Model the part-time scenario explicitly. What would 3 years of part-time look like at your current skills and salary? What would you need to earn to meaningfully move the needle?
Each of these five decisions intersects with the others. Your Social Security timing affects your tax strategy. Your healthcare bridge affects your part-time bridge math. Your asset allocation affects your sequence of returns risk.
The goal is not to optimize each decision in isolation — it is to understand how they interact so you can make them intentionally, not by default.
Pick the one decision on this list where you have the least clarity. Spend 30 minutes this week doing just that research. Not all five — just one. Decision paralysis kills more retirement plans than bad markets do.
Disclaimer: This is educational content, not financial advice. Every situation is different. Work with a fee-only fiduciary for decisions specific to your circumstances.