Guide · Tax rates

Your tax bracket is not your tax rate — what your next $1,000 really costs

There are three different rates hiding behind the phrase "my tax rate," and they can be far apart. The one you can look up on a bracket chart is rarely the one you need. For a retirement-income decision, the number that matters is what your next dollar actually costs — and it's usually higher than your bracket.

Three rates that aren't the same

Start by separating them. Your statutory bracket is the rate on your last dollar of ordinary income — 12%, 22%, and so on. Your effective rate is total tax divided by total income, and it's usually much lower, because your first dollars are taxed at lower rates and some of your income isn't taxed at all. Your true marginal rate is what your next dollar of income actually costs. People reach for the bracket when they mean the marginal rate, and the two only match in simple cases.

Why the effective rate runs low

Your income doesn't all get taxed at your top bracket. It fills the brackets from the bottom up, and your standard deduction shields a slice off the top before any of it is taxed. So a household in the 22% bracket might pay an effective rate closer to 12%. That's the number that describes your whole return — but it says nothing about the cost of doing something new, like a withdrawal or a conversion.

Why the marginal rate runs high in retirement

Here's the part that surprises people. A withdrawal from a traditional IRA is ordinary income, taxed at your bracket. But it doesn't stop there. That same dollar of ordinary income can push preferential income — your qualified dividends and long-term capital gains — up out of the 0% capital-gains tier and into the 15% tier, and it can pull more of your Social Security into taxable income. Each of those effects stacks on top of the bracket. The result is a true marginal rate well above the rate any bracket chart shows.

A worked example

Why this is the number that matters

Almost every retirement-income decision is a "should I add more income this year" question: how much to withdraw, whether to convert, when to realize a gain, how to sequence accounts. Each of those turns on what the next dollar costs — the marginal rate — not the bracket and not the effective rate. It's the single most useful figure for the decision in front of you, and it's the one no lookup table shows.

How Harbor handles it

Harbor computes your true "next $1,000" figure directly, by running your return with and without that income and reading the difference — so it captures the capital-gains displacement and the Social Security effect automatically, not just the bracket. It shows the bracket, the effective rate, and the real marginal rate side by side, for the tax year you're modeling, so you can see how far apart they are for your own numbers before you decide anything.

Common questions

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