His best frescoes were a historical series painted on the walls of a new palace at Caprarola, built for Cardinal Alessandro Farnese, for which Taddeo also designed a great quantity of rich decorations in stucco relief after the style of Giulio Romano and other pupils of Raphael. Nearly all his paintings were in fresco, very large in scale, and often in chiaroscuro or monochrome; they were more remarkable for rapidity of execution and a certain boldness of style than for any higher qualities. His work is mannered in style, artificial and pompous in conception, and lacks any close or accurate knowledge of the human form and its movements. He died in Rome in 1566, and was buried in the Pantheon, not far from Raphael.
Taddeo's easel pictures are less common than his decorative frescoes. A small painting on copper of the Adoration of the Shepherds, formerly in the collection of James II, is now at Hampton Court; it is a work of very small merit. The Caprarola frescoes were engraved and published by Prenner, Illustri Fatti Farnesiani Coloriti nel Real Palazzo di Caprarola (Rome, 1748-50).