Regardless if it is march, june, september, november, individual or corporate, I've been wondering if the deadline of last day in the month is for sending the docs or the tax office receiving them

Sending.

However, I am normally a few days or weeks late.

Tom

Really? that would seem strange to me, however I've never had any problem when I've sent the papers a day or two late, when the electronic transfer was done before the deadline.