The DIY Retirement Planning Guide

Why plan your own retirement

A comprehensive financial plan from a certified financial planner costs $2,000–$5,000 upfront, plus ongoing advisory fees of 0.5–1% of assets under management. For someone with $500,000 saved, that is $2,500–$5,000 per year — every year — for advice that often amounts to generic asset allocation and a set of projections printed once and never updated.

DIY planning does not mean guessing. It means using tools that model your specific situation — your balances, your income, your state's tax rules, your expected retirement age — and showing the year-by-year outcome of each decision before you make it. The math has always been accessible. What changed is that software can now run it connected across all the variables at once, rather than treating each decision in isolation.

The five decisions that matter most

Most retirement advice overwhelms you with dozens of variables. In practice, five decisions drive the vast majority of your outcome.

What you need to model

A real DIY plan is not just savings times a growth rate equals a future number. You need to model the interactions between multiple systems that most people — and most advisors — treat separately.

Federal taxes are the first system. Each year's withdrawals, Social Security income, and any earned income push you into different brackets. The order you withdraw from accounts changes which bracket you land in and how much of your benefit gets taxed. A $70,000 withdrawal from a traditional IRA in a year when Social Security is also flowing can put you in a 22% bracket on income you would have taxed at 12% had you drawn from Roth instead.

RMDs are the second system. Starting at age 73, the IRS forces you to withdraw a percentage of your traditional account balance each year regardless of whether you need the money. At 73 that percentage is roughly 3.8% and it rises every year. A couple with $1.5 million in traditional accounts will face combined RMDs of over $56,000 per year at 73, stacked on top of Social Security, whether they planned for it or not.

Medicare IRMAA is the third. Income above certain thresholds triggers surcharges on Medicare Part B and D premiums — up to $600 or more per person per month above the standard cost. Because the surcharge is based on your income from two years prior, a large Roth conversion or traditional withdrawal today shows up in your Medicare bill two years from now. Your conversion strategy needs to model this lookback explicitly.

ACA marketplace subsidies are the fourth if you retire before Medicare begins at 65. Premium tax credits are calculated as a percentage of the Federal Poverty Level, and crossing 400% FPL eliminates the entire subsidy with a single dollar of extra income. A Roth conversion that crosses that line in a year when you are on marketplace insurance can cost more in lost subsidies than the tax benefit of converting.

Social Security taxation is the fifth. Up to 85% of your Social Security benefit can be subject to federal income tax depending on your combined income. The thresholds are not indexed for inflation, which means more retirees cross them each year. The timing of your other withdrawals directly affects how much of your benefit you keep. No single one of these systems is complicated on its own. The challenge is modeling how they interact across 30 years, and that is precisely what ThunderHarbor does.

How ThunderHarbor maps to each decision

ThunderHarbor is built around the specific planning decisions that move the needle most. Every major tab connects to a concrete retirement question. The table below maps the key decisions from this guide to the tool that handles them.

All tools share the same underlying projection, so a change in one place — your Social Security claiming age, a Roth conversion amount, a spending adjustment — flows through every other tab automatically.

When to get professional help

DIY planning works well for most straightforward situations: W-2 income, 401(k) and IRA savings, standard Social Security timing. If your situation involves complex estate planning, business ownership, stock options, pension elections, or multi-generational wealth transfers, a good advisor earns their fee on those specific questions.

The most efficient approach for many people is a hybrid: use tools to understand the math and form your own views, then validate your plan with a fee-only advisor — one you pay by the hour, not one who takes a percentage of your assets. You will get better advice because you are starting from an informed position, and you will spend less because you have already done the heavy lifting. ThunderHarbor's year-by-year projection and concern-aware summary report give you a clear document to bring into that conversation.