"Now there was no bread in all the land; for the famine was very severe, so that the land of Egypt and the land of Canaan languished because of the famine. And Joseph gathered up all the money that was found in the land of Egypt and in the land of Canaan, for the grain which they bought; and Joseph brought the money into Pharaoh's house. So when the money failed in the land of Egypt and in the land of Canaan, all the Egyptians came to Joseph and said, 'Give us bread, for why should we die in your presence? For the money has failed.' Then Joseph said, 'Give your livestock, and I will give you bread for your livestock, if the money is gone.' So they brought their livestock to Joseph, and Joseph gave them bread in exchange for the horses, the flocks, the cattle of the herds, and for the donkeys. Thus he fed them with bread in exchange for all their livestock that year" (Gen. 47:13-17).
When God said seven years, He meant it! The famine would consume the years of plenty, as had been prophesied. After all the people ran out of money, Joseph began trading them food for their livestock. This enabled them to survive another year.
"When that year had ended, they came to him the next year and said to him, 'We will not hide from my lord that our money is gone; my lord also has our herds of livestock. There is nothing left in the sight of my lord but our bodies and our lands. Why should we die before your eyes, both we and our land? Buy us and our land for bread, and we and our land will be servants of Pharaoh; give us seed, that we may live and not die, that the land may not be desolate.' Then Joseph bought all the land of Egypt for Pharaoh; for every man of the Egyptians sold his field, because the famine was severe upon them. So the land became Pharaoh's. And as for the people, he moved them into the cities, from one end of the borders of Egypt to the other end. Only the land of the priests he did not buy; for the priests had rations allotted to them by Pharaoh, and they ate their rations which Pharaoh gave them; therefore they did not sell their lands" (Gen. 47:18-22).
It would seem likely that Joseph redistributed the population close to the places where the grain was stored. Surely there is more that could have been written about this, but Moses is merely highlighting events from a five-year period (cf. 45:11).
"Then Joseph said to the people, 'Indeed I have bought you and your land this day for Pharaoh. Look, here is seed for you, and you shall sow the land. And it shall come to pass in the harvest that you shall give one-fifth to Pharaoh. Four-fifths shall be your own, as seed for the field and for your food, for those of your household and as food for your little ones.' So they said, 'You have saved our lives; let us find favor in the sight of my lord, and we will be Pharaoh's servants.' And Joseph made it a law over the land of Egypt to this day, that Pharaoh should have one-fifth, except for the land of the priests only, which did not become Pharaoh's" (Gen. 47:23-26).
The people were grateful for Joseph's foresight to store up all the grain that he did. True, they were now servants of Pharaoh, but they were alive! They were more than willing to give up all of their possessions and embrace a 20% agricultural tax if it enabled them to survive. It is unknown how many thousands of lives Joseph saved. This famine changed Egypt radically and made Pharaoh exceedingly rich. He now owned all the land (cf. Lev. 25:23). One benefit of this 20% tax was that it would enable the rulers to store up grain for any future famines. The priests and Joseph's family were exempt from the tax.