"... a report needs [to be filed] with the customs office." The use of "needs filing" is colloquial. I think it's a matter of replacing "require" with "need" - the verb "require" is always followed by a noun or gerund. (Fellow native speakers, please comment if I'm wrong about "needs [verb]ing!) Because the sentence is talking about a possibility, it makes much more sense to use the infinitive: to be filed.