Moses (1513-1515), Carrara marble, 235 cm (92.52 in), San Pietro in Vincoli, Rome.  Photo by Prasenberg, Creative Commons Attribution 2.0 Generic license here.

He helped many poor people, says Vasari, and secretly provided dowries for many young girls. He gave two thousand crowns (or ducats: they seem to have been equivalent, or nearly so) in a lump sum to his servant and companion Urbino.
He also gave away free many of his drawings and models and cartoons and even statues worth thousands of ducats to friends of his. Would a miser do that? asks Vasari.

But it was to his relatives that he was most generous. He always felt it a duty to look after them. Most of his hoarded money was sent to his father, his brothers, and his nephew. He would give his nephew three and four thousand crowns at a time; and at the end he left him ten thousand crowns, along with his property in Rome.
He bought his father a farm and sent him enough money to live comfortably in old age.
He set up his brothers in business and so gave them a livelihood.
He helped the family when they had to leave Florence during a dangerous change of government there, and also when they came back, to get established again.
The letters show how generous he was to them. And all the complaining about his own mistreatment by patrons has to be seen as a sort of dog-snarling while he fights for his sustenance rather than dog-whining or idle howling.

Also the snarling that a dog does to keep other dogs away from his bone. His relatives soon got used to the idea that their Michelangelo was a money-bags and they often came around with hard-luck stories. Naturally, Michelangelo was skeptical and played tough; he frowned and stormed sometimes and wagged his finger and lectured them while they nodded and waited for the conclusion. Many of the letters are these lectures and complaints and admonishments introductory to the shelling out. His relatives realized that his sense of duty would do the trick for them and he could be counted on for the money. However much he snarled, he would turn over the bone.

Of course the old Master didn’t like to be considered rich—no miser does. And his two biographers, who loved him, helped his cause by amending the figures of the money he was known to have earned, making them smaller. For instance, Vasari says that the original idea for the Sistine Chapel ceiling was for Twelve Apostles and little more, and Michelangelo’s pay was to be fifteen thousand ducats. That original plan was thrown out. Michelangelo then covered the ceiling with hundreds of figures and worked for at least two years; and was finally paid, according to both biographers, three thousand ducats. Something is wrong somewhere. He must have received much, much more. If he hadn’t, the reader of his letters would have heard a wail ascend to heaven, sure.

And the very fact that the biographers stop giving figures for his remuneration of such labors as the wall of the Sistine or the frescoes in the Pauline Chapel must mean that Michelangelo was satisfied with them and so kept them to himself rather than howl; or that the biographers thought it indiscreet or impolite to publish the figures and let the world see just how lordly they were. The sweat of some brows comes out gold. No use creating more envy than there already was.

See  How Did Michelangelo Get So Rich? to learn where his money came from.

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