You have a plumber, electrician, babysitter, etc. doing a job for you. There is a Mitzva of "Byomo Titein Schoro" paying in the same day. If you pay by check, where the person has to first go to the bank and cash it, and may not get to it until the following day, is it considered "Byomo Titein Schoro"?
The mitzvah of Byomo Titein Schoro/Lo Tolin is made up of an aseh and a lo ta'aseh.
According to The Halachos of Other People's Money by Rabbi Bodner, paying by check paturs you from both, i.e. you didn't do the aseh, but you didn't violate the lo ta'aseh.
R' Ezra Basri (in Dinei Mamonot) doesn't discuss whether you fulfill the aseh, but he does say "A worker need not be paid in cash. A check is also sufficient. Similarly, an employer may arrange for a bank or finance company to pay his workers."