What is Estimated Tax?
Estimated tax is the method used to pay tax on income that is not subject to withholding, such as self-employment income, interest, dividends, rents, alimony, etc. In addition, if you do not elect voluntary withholding, you should make estimated payments on other taxable income, such as unemployment income and the taxable portion of social security benefits. 

To reflect the recent increase in gas prices, the IRS raised the standard mileage rates for six month period from 7/1/08 through 12/31/08. The rate will increase to 58.5 cents per mile for business miles driven from 7/1/08 through 12/31/08, an eight cent per mile increase from the rate in effect for the first six months of 2008 [see Rev. Proc. 2007-70 (2007-50 IRB 1162) ]. The rate for computing deductible medical or moving expenses will also increase by eight cents per mile to 27 cents per mile, up from 19 cents per mile for the first six months of 2008. The rate for providing services for a charity is set by statute, and remains at 14 cents per mile. IRS Ann. 2008-63, 2008-28 IRB .

The Treasury Department and Internal Revenue Service issued new guidance on the maximum contribution levels for in 2009 for Health Savings Accounts (HSAs) and out-of-pocket spending limits for High Deductible Health Plans (HDHPs) that must be used in conjunction with HSAs. These amounts have been indexed for cost-of-living adjustments for 2009. 

If you haven't contributed funds to an Individual Retirement Arrangement for tax year 2007, or if you’ve put in less than the maximum allowed, you still have time to do so. You can contribute to either a traditional or Roth IRA until the April due date for filing your tax return for 2007, not including extensions.