My instinct is that this is saying that, in calculating the customer's balance, any cheques paid in will be taken into account as long as they do not have to go through an international clearing process before being properly credited to the account.

In this context, therefore, I suspect "encaissement" is equivalent to the EN term "collection" as applied to foreign cheques paid into a UK bank account.

I don't have to time to research this any more thoroughly, hence only a medium confidence rating, but here's one link that kind of supports my suggestion:

http://groupe.socgen.com/banks/fr/banks-financial-institutio...

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Note added at 1 hr (2010-01-09 18:36:17 GMT)
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See also http://www.lloydstsbcorporatemarkets.com/corporateservices/t...

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Note added at 23 hrs (2010-01-10 16:48:27 GMT)
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Having re-read this and thought about it after a fresh dose of coffee, I still feel this is the most likely interpretation, and that rkillings' phrasing is probably the most efficient way of putting it.