Retirement tax questions

Thank you for your quick and informative reply. The part that confuses me is whether my continuing working part time (with the same employer after my retirement this year) will allow me to delay taking the RMD from either my 403b plan or the employer sponsored voluntary investment plan. I was told by some that  i don't have to take RMD as long as i am still employed by the same employer (even part time after i am formally retired). Is that correct? Don't want to be penalized if i don't take the RMD when i am supposed to... Thanks!