Many of our customers had their chimney fixed multiple times, only to have it leak again during storms with high winds and rain.  Although the roof’s flashing had been redone and did not fix the leak 100%. We often time see that their chimneys had cracks in the mortar and usually the crown as well this which  allows a driving rain to penetrate. However we often also find chimney that had been repointed in the past, therefore  we take a step further by grinding out and redoing the mortar, which fixes their chimney leaks. Make sure the masonry aspect of your chimney is in good conditions, as the chimney is the part of your house that is exposed to all the elements it is most likely that moisture could be penetrating.