Codes 4 and G together indicate that the Form 1099-R is reporting a rollover from a decedent's employer plan like a 401(k) to an inherited retirement account, usually to an inherited traditional IRA (nontaxable) or to an inherited Roth IRA (taxable) (although some plans allow a spouse beneficiary to establish an inherited account in the employer's plan). Any taxable amount shown in box 2a implies that the rollover was to a Roth IRA.