Please provide more details and clarification.
An RMD is not an account or a retirement benefit. It's money that you had to withdraw from a retirement account of some kind, usually an IRA. Did you take the RMD from a traditional IRA?
You should have received two 1099-R forms, one for the RMD and one for the pension. The 1099-R forms come from whoever paid the RMD and the pension to you. You have to enter each 1099-R separately in TurboTax. I'm not sure what you mean by the "TurboTax pensions form." Do you mean the screen where you enter a 1099-R?
Where exactly do you see the codes X and G? It's not clear what those codes are. Can you post screen shots? (Make sure there is no personal information in the screen shots. This is a public web site.) If you had the RMD and the pension last year, and you used TurboTax last year, TurboTax might have copied some of the 1099-R information from last year, including the codes. That could be what you are calling "preloaded." But you have to make sure that what you enter this year matches the forms that you received from the payers. You can change what was copied from last year if necessary.
The general rule would not apply to an RMD.
