Smurfing is a common name for structuring, the practice of splitting a large sum of money into many smaller transactions to avoid reporting thresholds and the attention of banks and authorities; the main entry covers the legal offence and how it is investigated. The word usually stresses the use of several people, known as smurfs, who each deposit cash or buy monetary instruments in amounts that stay below the limit.
In a typical scheme, a launderer recruits individuals to visit different bank branches, money transfer agents or shops on the same day, each paying in cash just under the level that would trigger a currency transaction report. The funds are then consolidated and moved on. Smurfing is therefore a classic technique of placement, the first stage of money laundering, and overlaps with the use of money mule networks.
Some writers distinguish the two terms, using structuring for one person splitting their own transactions and smurfing for schemes using many helpers, but laws generally treat both as the same offence. Banks detect them through transaction monitoring rules that aggregate related deposits across accounts, branches and days.