Home business travel expenses aren't deducted 1 for 1?

[psaf]

When I entered a travel expense of, say $100, I only saw my Federal Tax Due amount reduce by a much smaller amount, like $20 or something. Are business travel expenses not a 1 for 1 deduction?

[jerry2000]

No that is not a 1 for 1 reduction in your tax, only a tax credit does that. A deduction reduces your tax by reducing your taxable income. The maximum tax benefit is the deduction times your marginal tax rate. So if you are in the 20% tax bracket, a $100 deduction reduces your tax by $20.