Grannyknot
How about a list of current competitions at the top of the Competitions home page, with either an end date or "Open" next to it as applicable...
All the competitions on our competitions index are live - we take them off once the competition has closed.
For competition pages, the closing date is under the 'how to enter' section and for thread competitions, they are usually stated nearer to the end of the OP.
There are a handful of competitions on threads which have an open end date, as LaraGransnet said. If we haven't specified a closing date, then consider it open - we would have 'now closed' in the thread title or within the post otherwise.
HTH 