An insulated reductant tank that is arranged so that it has an insulated upper portion and a tapered lower portion, the reductant tank configured to allow frozen reductant to move into the insulated upper portion and reduce the damage that frozen reductant can cause to a reductant tank when the frozen reductant expands. The insulated reductant tank can include at least one header configured to draw reductant from the reductant tank and supply the reductant to an exhaust aftertreatment system, an insulation layer lining an upper portion of the reductant tank, a tapered lower portion, and at least one baffle configured to control a flow of reductant.