IAT monitoring is just like any other type of foreign transaction monitoring. Compare the values, volumes, and velocities of the transactions to what you would expect given the customer's profile. In addition, you should consider jurisdictional factors, such as the risk of the counterparty's country and whether or not their jurisdiction has funds transfer reporting requirements they may be trying to evade (e.g. Canada) by unnecessarily splitting the transactions (you would have to research exchange rate data to perform this analysis properly). Also, pay particular attention to unexpected even dollar transfers (e.g. supply purchases), cash-funded outgoing IATs, incoming IATs preceding cash withdrawals, multiple customers receiving IATs from the same unique source, and multiple customers sending IATs to the same unique source.
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CFE, CAMS