The verso is a study for the left side of the cupola of the apse of Santa Sabina, Rome, datable to 1559-60, C. Acidini Luchinat, Taddeo e Federico Zuccari, Rome, 1988, I, p. 114, fig. 19. The cupola represents Christ on a mountain sitting by a spring, surrounded by apostles and saints. The composition is based on a medieval mosaic which was destroyed during repairs to the cupola and replaced by Taddeo's fresco. The three foreground figures in our drawing appear in the cupola, although they are more widely separated. Some of the background figures are also found in the fresco, but again in different positions.
A preliminary study for the entire composition is in a private collection in Paris, C. Acidini Luchinat, op. cit., p. 116, fig. 23.
The figure executed in red chalk on the recto was drawn after a model and may be a study for one the apostles who wears an identical hat on the left of the Assumption of the Virgin in the Pucci chapel in the church of Trinità dei Monti in Rome, which Taddeo was painting at the time of his death, C. Acidini Luchinat, op. cit., p. 271, fig. 15. A figure on the left of the Flagellation in the Mattei Chapel also wears an identical hat and has a similar facial expression.
The attribution has kindly been confirmed by James Mundy.