Military pensions are taxable on a federal tax return. How much federal income taxes should be withheld is dependent on your filing status, age and the amount of other taxable income being reported on the tax return.
Go to this IRS website for the W-4P, Withholding Certificate for Pension or Annuity Payments, use the worksheets to determine your federal withholding - https://www.irs.gov/pub/irs-pdf/fw4p.pdf
If you are a California resident the military pension is taxable on the state income tax return.
Go to this California website for the form DE 4P, WITHHOLDING CERTIFICATE FOR PENSION OR ANNUITY PAYMENTS, use the worksheets to determine your state withholding - https://edd.ca.gov/pdf_pub_ctr/de4p.pdf
