Can my landlord charge me a $100 a day late fee on my $679 a month rent?

Most statutes have statutes setting the maximum amount that one can be charged a late fee for rent, typically a percentage of the monthly rent such as 10%.

If your rent is $679, then under your state's statutes perhaps the maximum amount allowed to be legally charged is $67.90. I suggest that you might want to call a landlord tenant attorney about the seemingly excessive rent being charged you for a late fee to see if the $200 amount is in compliance with your state's laws or not.