A lot of people are applying for jobs at the moment, which means I’m proofreading a lot of cover letters.
I am writing in regards to the job advertised on . . .
Stoooop! (*sound of screeching brakes*) Even though it’s very common, “in regards to” is a mistake. You can write “in regard to”, “with regard to”, “having regard to”, “as regards” or “regarding”, but never “in regards to”.
Admittedly, a quick google tells me “in regards to” is actually more common than “in regard to” these days. Plenty of potential employers won’t identify it as a mistake. However, some will, and they probably have a David Brent-style “special filing cabinet” for such applications. Do you want to take that risk?