A system and method are provided for a sampled accumulation method that maps information into Synchronous Payload Envelopes (SPEs). The method buffers data from a plurality of tributaries, and sequentially stores buffer-fill information for each tributary in a first memory, at a rate of up to one tributary per system clock (Fsys) cycle. A stored accumulation of buffer-fill information for each tributary is updated at a sample rate frequency (Fsample), where Fsample≦Fsys. The stored accumulation of buffer-fill information is used to calculate stuff bit opportunities for each tributary. As a result, the rate of data being mapped into outgoing tributaries is regulated, and the outgoing mapped tributaries are combined in a SPE.