amyonghwee,
The IRS says in the instructions for Form 1099-R:
"Use Code G for a direct rollover from a qualified plan, a section 403(b) plan, or a governmental section 457(b) plan to an eligible retirement plan (another qualified plan, a section 403(b) plan, a governmental section 457(b) plan, or an IRA). See Direct Rollovers, earlier. Also, use Code G for a direct payment from an IRA to an accepting employer plan, and for IRRs that are direct rollovers.
Note. Do not use Code G for a direct rollover from a designated Roth account to a Roth IRA. Use Code H.
This says there are two scenarios under which you would have gotten that 1099-R with code G. Your description isn't clearly telling me where the money originated and where it was deposited, nor whether the the receiving account was an employer Roth plan. Do you mean that you converted, say, a regular 401K plan to a Roth 401K plan? My wife did this some year ago and, of course, paid the tax due as a result.
