From SB Nation:
Teams are allowed to go over their total bonus pool allotment, but even going over by small amounts incur harsh penalties. If a team exceeds their budget by between 0-5 percent, they are taxed 75 percent on the amount they went over. If they exceed the budget by 5-10 percent, they suffer the same penalty as 0-5 percent plus they lose their first-round selection in the following draft. Going over by 10-15 percent incurs a 100 percent tax on the overage, plus the loss of first- and second-round picks in the following draft. Anything over 15 percent results in the team paying a 100 percent tax on the overage and the loss of their first-round selection for the next two drafts.