When it comes out, Shift Bidding would allow for this, but until then you could try creating a user called OT and place that in the scheduling. Then allow agents to swap with that user. You will need to put that user in their own work plan to allow for the reduced hours or just put the hours in manually.
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Robert Wakefield-Carl
Avtex Solutions, LLC
Contact Center Innovation Architect
robertwc@avtex.comhttps://www.Avtex.comhttps://RobertWC.Blogspot.com------------------------------