A deck post should always be placed on top of footing, not inside concrete because it can break. The photo on the left shows a post set in a bracket that has been mounted to the top of a footer. The photo on the right shows a post that has concrete poured around it, which can lead to a crack like you see here. When concrete is poured around a deck post in this way, the post will rot due to moisture buildup by the soil. Concrete tends to absorb moisture and wood expands when it gets wet, so these two factors combined will result in the wood breaking the concrete. By setting the post on top of footing, you’re creating a solid foundation for the deck to stand on.