Is $38,000 your only income?
Are you married?
Do you have dependents?
Do you own a home?
Do you have any other deductions?
You would like to know how much your tax will be for 2009. Correct?
I will need a breakdown from you.
What amount will be SS?
What are your investments? What portion of the $38,000 come from them?
You say "a little salary" but you mentioned you have retired in 2008. Do you mean a pension?
Your SS is going to be partially taxable. Half of the SS benefits are added to your other income, including income excluded from tax. If that amount is over $32,000 (for married filing joint in 2007), part of your benefits will be taxable.
I used the tax calculator on hrblock.com (http://hrblock.com/taxes/tax_calculators/index.html) and input the figures you have given me. Remember, this is a tax year 2007 estimate.
It appears if your spouse has 11% of her pay withheld for federal taxes, you will not need to have taxes withheld from your SS. It will cover the entire amount of taxes you owe for the year. This is calculating that $5,750 of your SS will be taxable.
This answer may need to be adjusted in 2009, depending on the standard deduction amount and personal exemption amount. However, if your figures remain the same (and are not more), the amount of tax that needs to be withheld will be less (as the standard deduction and personal exemptions amount increase every year).
Please let me know if I can help you further.