Tax Deduction Calculator
See what a deduction actually saves you at your marginal rate.
Please note: A general estimate, not tax advice. Rates, bands, allowances and rules differ by country and change frequently. Enter the figures that apply to you and confirm with a qualified tax professional or your tax authority.
What the Tax Deduction Calculator does
A deduction reduces taxable income, so its value depends on your marginal rate — not the full amount. Spending money purely to claim a deduction always costs more than it saves, since you only recover a fraction.
Formula
Deduction claimed = max(Standard deduction, Itemised total)Tax saving = Deduction × Marginal rateNet cost of a deductible expense = Expense × (1 − Marginal rate)
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Gross income | selected currency | Yes | Accepts more than 0. |
| Your marginal tax rate | % | Yes | — |
| Standard deduction | selected currency | Optional | Accepts 0 or more. |
| Itemised deductions | text | Optional | Mortgage interest, charitable giving, medical costs and so on. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Currency.
- Enter Gross income and Your marginal tax rate.
- Optionally add Standard deduction and Itemised deductions.
- Select Calculate.
Worked example
$95,000 income at a 24% marginal rate, $14,600 standard versus $19,300 itemised.
- Income
- 95000
- Rate
- 24
- Standard
- 14600
- Itemised
- 12000, 4500, 2800
Itemising wins at $19,300, saving $4,632 — $1,128 more than the standard deduction.
Frequently asked questions
Should I itemise or take the standard deduction?
Whichever is larger. Itemising only pays once your qualifying expenses exceed the standard amount, and then only on the excess.
Is a deduction better than a credit?
No. A $1,000 credit saves $1,000. A $1,000 deduction saves only your marginal rate — $220 at 22%.
Method and sources
Method. Compares the standard deduction entered against the itemised total, applies whichever is larger, and reports the tax saved at the marginal rate.
Assumptions
- The itemised amounts listed are all actually deductible, and the choice is genuinely between standard and itemised.
- The saving is valued at the marginal rate, which holds while the deduction does not drop income into a lower band.
Limitations
- Whether a category is deductible at all, and any cap or floor on it, is jurisdictional and changes often.
- A deduction reduces taxable income, not tax. Its worth is the amount times your marginal rate, which is why the same deduction is worth more to a higher earner.
- No rate table ships with this calculator: you supply the rates, so the result follows whichever jurisdiction and year you enter. That means it can never go silently out of date — but it also cannot warn you if the figures you entered are.
Sources
- Your own tax authority's published guidance for the relevant year — Varies by jurisdiction. The standard deduction amount, which expenses qualify, and the caps that apply to each.