Can I set a "must be submitted" date that is different to the event active date?

No, The Redbourne Platform, to keep things simple and avoid confusion, works on one date and that is the active date set for an event. Say on a site the New Benefit Year active dates have been set for 1st April. The "countdown" on the benefit table is based on this date e.g. "please submit immediately..." if the date has passed.

Based on our experience across all the schemes we operate there are always a number of people that do nothing until after a deadline! So even if you can tolerate changes up to, say, the 8th of the month we would recommend that you set the active date at the start of the month to encourage people to submit their choices before the real deadline. Otherwise there is a real risk of late submissions delaying reports which in turn delay payroll etc.