The narrator tells us that, in the past, when Cratchit has asked Mr. Scrooge for additional coal to warm the office, "the master predicted that it would be necessary for them to part." In other words, when Cratchit attempts to procure more coal for Scrooge's office, Scrooge threatens to fire him!
However, Cratchit doesn't technically ask Scrooge for the day off. It is Scrooge that brings it up, saying, "'You'll want all day to-morrow, I suppose?'" And it is, again, Scrooge that suggests Cratchit would expect to be paid for this holiday off, asking, "'If I was to stop half-a-crown for it, you'd think yourself ill-used, I'll be bound?'" In other words, he implies that Cratchit would feel it to be unjust if he weren't paid for the day, though the clerk, himself, never actually says it aloud. Scrooge is bitter, to be sure, but Cratchit doesn't technically ask him for the day off, or to be paid for it; Scrooge merely anticipates the request.
Finally, after the visitations of the three ghosts, on the day after Christmas, Cratchit returns to work; however, he is nearly twenty minutes late. When Scrooge brings it to Cratchit's attention, Cratchit apologizes for his lateness, acknowledging his responsibility to be prompt. When Scrooge orders him into Scrooge's office, Cratchit says,
"It's only once a year, sir . . . It shall not be repeated. I was making rather merry yesterday, sir."
Here, Cratchit implicitly requests forgiveness for his lateness from Scrooge. He assumes that he will not be fired when he states that he won't repeat the behavior, and he offers as his excuse that he's only ever late this one day per year and that he'd been "making merry" the night before (as, presumably, he never does but once per year). Therefore, Cratchit does, in a way, ask forgiveness for his lateness.