Pre-tax deduction inputs: 401(k), IRA, HSA
The three fields aren't interchangeable behind the scenes, and the calculator treats them differently on purpose. A 401(k) contribution and an HSA contribution are both modeled as payroll deductions: they reduce federal taxable income and reduce the wages the tool uses for the FICA calculation (Social Security and Medicare). A Traditional IRA contribution only reduces federal taxable income — the FICA figure doesn't move, because IRA contributions are typically made outside of payroll.
As an example only, take a Single filer with $75,000 gross income entering $6,000 into the 401(k) field on the 2025 Take-Home Pay tab. Taxable income for federal tax purposes drops to roughly $54,000 after the $15,000 standard deduction, and the wages used for the FICA calculation also drop by that $6,000. If the same $6,000 were entered into the Traditional IRA field instead, federal taxable income would drop the same way, but FICA would still be calculated on the full $75,000.
Tax year selector: 2025 vs 2026
Previously the tool only worked with 2025 figures. Adding 2026 as a second option means you can now compare the same income and filing status across two years side by side, without leaving the page — useful heading into a new year when bracket thresholds and the standard deduction shift with inflation. Select 2025, note the result, switch the dropdown to 2026, and recalculate with the same income entered to see the difference.
Child Tax Credit field
This is the piece that was missing before: the calculator could already show you your bracket-based tax, but it had no way to account for a credit reducing that number further. Credits and deductions aren't the same kind of adjustment — a deduction (like the standard deduction, or a 401(k) contribution) shrinks the income that gets taxed, while a credit subtracts straight from the tax bill itself, dollar for dollar. Because a credit isn't scaled by your bracket, its effect on the final number can be larger than a deduction of the same size for many filers.
As an example only, a Single filer entering "2" in the qualifying children field, with income well under the phase-out threshold, would see up to $4,000 subtracted from their estimated federal tax owed on the Take-Home Pay tab — on top of whatever pre-tax deductions and bracket math already applied. The phase-out means this benefit narrows for higher earners rather than disappearing at a single cliff.
Using all three together
The three additions are designed to be used at the same time on one tab, which is the more realistic scenario for most people planning around a paycheck: you have a filing status, you're choosing a tax year, you're deciding how much to put into a 401(k) or HSA, and you may have dependents. Enter your gross income, filing status, and tax year first, then fill in whichever of the 401(k)/IRA/HSA fields apply, then the number of qualifying children, and the Take-Home Pay result reflects all of it together — federal tax after deductions and the credit, FICA on the appropriate wage base, and an estimated take-home figure.
None of the new fields are required. If you only want the original federal-and-FICA estimate, leave the deduction fields and children field at their defaults and the calculation behaves the way it always has.