Find your taxable income without the deduction in the table in the 1040 booklet. Then find the tax amount in the chart that's $300.00 less and the income amount will be next to that.

For example, say your taxable income (before the deduction) is $45,200.00. The tax on that amount (for a single person) is $7,730.00. Your want to reduce your tax by $300.00 to $7,430.00. You'd have to reduce your taxable income by at least $1,150.00, to $44,050.00.

Here is a link that might be useful: 2007 Tax Table

I need to correct the last sentence to read:
You'd have to reduce your taxable income by at least $1,151.00, to $44,049.00.

So that means that charitable deductions are fully deducted from income: if my taxable income is $50,000 and I donate items worth $1,000, then my taxable income is now $49,000?

I thought only a percentage of charitable giving was tax deductable.

I think mona was referring to MONEY donated... not things.

I was referring to money or things. Yes, the deductions reduce your income dollar for dollar. There are limits explained in the link below.

Here is a link that might be useful: Charitable contributions - limits on deductions

In Canada, if I donate a stock certificate to a charity, I get a charitable receipt for the full amount of the value of the stock.

Plus ... I pay no tax on the capital gain that had been developed!

I like them apples!

ole joyful

Unless Congress changes tax law, you must itemize to be able to claim any charitable contributions.

Aye, that's the rub. Unless your other deductions exceed $10,000 (10,500?) for a couple, then the charitable contributions have no impact on your taxes.

I'm ineligible for the mortgage interest deduction because it's not enough. All my deducitons together only add up to ~$8,000. So, standard deduction it is.

Medical costs are only deductible once they exceed 7.5% of your income. IIRC everything else is dollar-for-dollar.