A rollover from a 401(k) to an IRA must always be reported on a Form 1099-R. Contact the former employer's plan administrator to obtain the missing form. In the case of a direct rollover, that Form 1099-R will have code G in box 7.
If the former employer's plan was not a 401(k) but was instead a SEP-IRA or SIMPLE IRA plan, a trustee-to-trustee transfer from one IRA to another would not be reportable on either a Form 1099-R or in box 2 of Form 5498.
