My wife reached the age of 70 1/2 in 2017 and set up a RMD for her federal government TSP. She received a form 1099-R in January and the IRA/SEP/Simple box was not checked. Does that mean that the RMD from the TSP is considered as just regular income and taxed at the marginal tax rate or is there a special rate similar to Capital Gains or other special rates that would be used? It increased our Federal tax more than we were expecting with an RMD.