Tax tools

Free calculators for what you actually owe — and what a raise, bonus, sale, or Roth conversion really costs you in tax. Every tool shows real numbers.

25 resources

Calculator 1099 Quarterly Estimated Tax Planner Calculate your quarterly estimated tax payments, self-employment tax, and safe harbor amount to avoid an IRS underpayment penalty. Open → Calculator 529 State Tax Deduction Real Value Calculator Most 529 state deductions look small on paper — see what that deduction actually compounds to by the time your child reaches college. Open → Calculator Additional Medicare Tax (0.9%) Exposure Calculator High earners pay a hidden 0.9% Medicare surtax on wages and self-employment income — find your exposure and total Medicare burden. Open → Calculator Backdoor Roth Pro-Rata Rule Tax Cost Calculator The backdoor Roth is not always tax-free — find the pro-rata portion that is taxable if you have other traditional IRA money. Open → Calculator Charitable Bunching & Donor-Advised Fund Tax Savings Discover how giving two years of donations in one year via a donor-advised fund can unlock itemization and save hundreds in taxes. Open → Calculator FSA Use-It-or-Lose-It Risk Calculator Find your FSA forfeiture risk and the exact break-even spending level where your tax savings outweigh what you might forfeit. Open → Calculator Gift Tax Annual & Lifetime Exclusion Planner Plan gifts to family members using the 2025 annual exclusion and lifetime exemption — and see the estate reduction from gifting now. Open → Calculator HSA Triple-Tax Lifetime Value Calculator Model the compounded advantage of the HSA triple tax benefit over a regular taxable account — three tax events, zero taxes paid. Open → Calculator Itemize vs Standard Deduction Real Benefit Calculator Calculate whether itemizing actually saves you money after the SALT cap — most filers are surprised how little they gain. Open → Calculator Marginal vs Effective Tax Rate Reveal Discover the gap between your headline marginal rate and what you actually pay — and how much income room you have before hitting the next bracket. Open → Calculator Mega Backdoor Roth Contribution Room Calculator Find how much after-tax 401(k) money you can convert to Roth beyond the standard deferral limit — and the lifetime value of that room. Open → Calculator Municipal Bond Taxable-Equivalent Yield Calculator Find the taxable bond yield you would need to match a tax-free municipal bond after your federal and state rates. Open → Calculator Net Investment Income Tax (NIIT) Exposure Calculator Find exactly how much of your investment income is hit by the 3.8% NIIT surtax and your true combined capital gains tax rate. Open → Calculator Roth Conversion Tax Cost & Breakeven Calculator Pay tax now, tax-free forever — find whether a Roth conversion pencils out at your rates and how long until the math flips in your favor. Open → Calculator RSU & Bonus Withholding Gap Calculator Employers withhold only 22% on RSUs and bonuses — find your exact shortfall if your marginal rate is higher and plan quarterly payments. Open → Calculator S-Corp Election Breakeven Calculator Find whether forming an S-corp saves more in self-employment tax than it costs in accounting fees — and how many months until you break even. Open → Calculator Short vs Long-Term Capital Gains Hold Breakeven See the exact tax savings from holding an investment 366 days instead of 365 — and whether the wait is worth it at your income. Open → Calculator Social Security Tax Torpedo Calculator Extra retirement income can trigger tax on your Social Security benefits, pushing your effective marginal rate far above your stated bracket. Open → Calculator Tax Bracket Fill-Up Planner Find exactly how much more income or Roth conversion fits in your current bracket before you cross into a higher rate. Open → Calculator Tax-Loss Harvesting Savings Calculator Find the exact federal and state tax you save by realizing a loss today — and whether it offsets gains or reduces ordinary income. Open → Calculator Traditional IRA Deductibility Phase-Out Calculator Find out how much of your traditional IRA contribution is still tax-deductible based on your income, filing status, and workplace plan coverage. Open → Calculator Withholding Opportunity Cost Calculator Your tax refund is an interest-free loan to the IRS — see exactly what that loan costs you in missed investment gains. Open → Guide How Much of My Bonus Actually Goes to Taxes — and How to Keep More Your bonus is not taxed at 40 percent — it is withheld at a flat 22 percent federal rate, and the difference is refundable. Here is the real math. Open → Guide Is a Roth Conversion Worth It? The Math, Honestly A Roth conversion pays off only if the tax rate you accept today is lower than the rate you would face later — here is the honest breakeven math. Open → Guide The HSA Is the Most Powerful Retirement Account Nobody Talks About A health savings account is the only account with a triple tax advantage — deductible in, tax-free growth, and tax-free out — and it doubles as a stealth IRA. Open →