Start here
The basics
Entering a higher bracket does not make every dollar of income taxable at the higher rate. Earlier slices keep their lower rates. The marginal rate applies to the next taxable dollar; the effective rate is total tax divided by a broader income measure.
Illustrative numbers
A deliberately simplified ladder
First $20,000 taxable10% = $2,000
Next $30,000 taxable20% = $6,000
Total tax on $50,000$8,000, or 16%
The top marginal rate is 20%, but the effective rate on taxable income is 16%. MoneyWhatIf repeats this slice calculation on the applicable federal and state schedules.
Calculation transparency
How it works in MoneyWhatIf
- 01
The code snapshot starts from 2026 federal schedules, deductions, and filing statuses; supported-state and selected-local schedules are still the 2025 published figures.
- 02
The model mechanically carries ordinary federal, state, and local schedules forward with plan inflation and configured rounding—even where a state may freeze its real thresholds. Separately encoded fixed items such as the Social Security, NIIT, and Additional Medicare thresholds stay fixed.
- 03
The household uses joint schedules while both partners are alive. A survivor with a dependent child keeps the joint schedule for up to two qualifying-surviving-spouse years; after that, and otherwise from the year after the death, the survivor’s years use single schedules.
Keep in mind
Model limits
The projection is not tax-return preparation and does not reproduce every credit, election, carryforward, deduction, or filing status.
A marginal bracket alone is not a complete strategy score; Social Security taxation, NIIT, state tax, and IRMAA may also change.
Future law is unknown. The page describes the model’s encoded rule snapshot, not a promise about future brackets.
This explanation documents the planning model. It is educational, not individualized tax, legal, Medicare, or investment advice.
Where it appears
Where to use it
See this concept in context, with a guide to each page and its controls.
The words behind it
Related financial terms
Plain-English definitions, with 2026 figures and worked examples, from the financial terms glossary.