Whether in Florence or Rome Filippo continued to stand by the Medici, ready to risk life and fortune in their service. The assistance he gave the family in war finance and through the depositories of the Signoria and of the Apostolic Chamber formed but part of his total financial involvement with the Medici papacy. In many ways, only after he had relinquished control of the Depository General in 1527 at the time of the Sack of Rome did he reach the peak of his career as a papal banker. During the subsequent period, 1529–1534, he made his biggest loans to the pope and took the greatest risks of his life. In the five years that ended with the pope's death in September 1534, he devoted his energies and his wealth unreservedly to his last remaining Medici patron and long-time friend, Giulio de'Medici, Clement VII.

We have already seen in our discussion of the Depository General in Rome how Filippo's credit dealings extended his participation in church finance and administration well beyond the duties connected with the Depository itself. In fact, in the course of his career as a banker to the Medici popes, Strozzi held nine other administrative positions, had title at various times to at least 258 venal offices and possessed a minimum of 80,000 ducats worth of Monte shares.