Generally speaking, "the timing" refers to the timing of a particular event, while "timing" tends to mean "timing in general". ) is required. For example, in the following case, the meaning can't be general: "The timing was all wrong" -- OK "Timing was all wrong" -- Wrong (except in a kind of "telegraphic" style of English) In your sentence it's already clear that "timing" refers to the timing of these specific expenses (rather than timing in general), and including or omitting "the" makes no difference to the meaning.
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