An aircraft tail assembly planform comprising curvilinear leading edges (21) and trailing edges (22), with an aircraft tail assembly configuration in which the hinge line (13) is rectilinear and has a non-constant percentage with respect to the chord (50) in each section (51), being the front (11) and rear (12) spars rectilinear with a non-constant percentage with respect to the chord (50) in each section (51), or being these spars (11, 12) curvilinear with a constant or non-constant percentage with respect to the chord (50) in each section (51). Moreover, the invention describes an aircraft tail assembly planform comprising rectilinear leading edges (21) and trailing edges (22), in which the hinge line (13) has a non-constant percentage with respect to the chord (50) in each section (51), being the front (11) and rear (12) spars rectilinear, with a constant or non-constant percentage with respect to the chord (50) in each section (51), or being these spars (11, 12) curvilinear, with a constant or non-constant percentage.