1. I don’t know what Ann does with all the money she earns, but I know she doesn’t spend it on herself. She must be salting it away for her retirement.
2. Sometimes we give food to the old man next door, because we know that he doesn’t have much money. Whenever we do, we try to give him enough so that he can salt some of it away for another day.

Compare to: on ice; save (something) for a rainy day. The expression originates from the practice of using salt to preserve food before storing it.