Retirement income is subject to income taxes in many states.
Federal Tax--Pension income is considered taxable income, and Social Security payments are also taxable depending on your total income, so don't think that you get 100% of the amount on your statement. And after you get Medicare at age 65, you have to pay about $125 a month out of your social security check for that insurance.
State Taxes--Pension income, Social Security, IRAs, all of these are treated differently by each state. Some exempt all or part of this income from STATE tax, but they cannot make any rules that stop the Federal government from taxing these. You should explore your state's rules on their website to learn how they treat these sources.
Another tidbit to consider is that if you take another job with income after you start taking Social Security, you may have to pay back $1 for every $3 earned prior to reaching age 70.
No matter what, however, you will be able to keep the vast majority of your retirement income, and hopefully it will allow you to live a comfortable fulfilling retirement.