Codes B and G together report a rollover from the designated Roth account in the 403(b) to a designated Roth account in the 401(k), 403(b), 457(b) or the federal TSP, not to a Roth IRA. If the rollover was indeed to a Roth IRA, you must ask the 403(b) plan to correct the Form 1099-R to have code H, not codes B and G.
