Just in case you have any cash left after this harrowing year and would like to rack up some additional deductions to claim on your 2008 taxes, you have until this Wednesday (Dec. 31) to do it.

Charitable contributions. The IRS considers checks to a charity “delivered” as of the date you mail them. The same is true for properly endorsed stock certificates you mail to a charity. Credit card contributions are deductible in the year you make the charge. These rules are explained in IRS Publication 526.

Business expenses. The rules for deducting business expenses vary, depending on your accounting method and whether you operate on a calendar or fiscal year. Those are explained in IRS Publication 538: Accounting Periods and Methods and Publication 535: Business Expenses.

If you miss out on these deductions, remember that you can still deduct a 2008 IRA contribution, assuming you meet the income limits and other requirements, as late as April 15, 2009 in most cases. Note that you have to use that deadline even if you file for an extension. For more on IRAs, see Publication 590.