Contrary to your misconception, u201c1099-Ru201d is not taxed.What is taxed is the income represented by the 1099-R.Now insofar as withholdings, itu2019s kind of problematic to calculate withholdings that would properly cover the taxes, assuming you have other sources of income.For W-2 income, for most people, that is the primary source of income. Thus the calculation for withholding is basically to take one pay periodu2019s worth of income, annualize it, determine the taxes based on that annualized rate, and then divide that by the portion of the year represented by that pay period (e.g. bi-weekly would be 1/26th of the year).If you have other sources of income (such as a pension) while youu2019re still getting other sources of income (whether a job or some other kind of income), then this is all marginal income. So the appropriate withholding would be at your marginal tax rate, i.e. the top rate. But unless you prenough information to determine this, this amount cannot be properly estimated.So while it appears that your pension income is taxed at a different rate, itu2019s u201cundifferentiatedu201d from other income, every extra dollar is taxed at the top rate which applies to you (i.e. your marginal rate), whether it comes from employment, pension, interest and dividends, etc (notwithstanding exceptions for specific types of income such as capital gains, social security, etc.)