Late fees in CA

[John McDermon]

I have a tenant 1 one year into a 2-yr lease in a 4 BR/3 Ba SFR in SoCal. He's a good tenant as far as taking care of the property and not complaining about the little things. But, recently he's begun to pay late. The rent is $3,000/mo, due on the 15th. There's a 10% late fee ($300) if he doesn't pay before the 20th (5 days). Whenever he's late he pays the late fee without complaint. However, he seems to be getting latter and later and now he's going to be almost a full month late. He's caught up in the past (briefly), so I've got my fingers crossed. My question is: in light of his habit of being later and later, is it legal in CA to have escalating late fees, say an addition $100/wk he's late after the initial 5-day grace period? If so, I assume I would need to renegotiate the lease or wait until his initial 2-year lease is up. Thoughts?