If you cut a player before June 1, then all of the dead money is immediately realized (in the current season).
If you cut a player after June 1, then you have to count any guaranteed money for that season plus the amount of the signing bonus that would have been prorated for that season. The rest of the dead money must be counted against the current season and/or the next season. You can divy it up between them if you like as long as it is all realized before the end of the next season.
Ex. Joe Linebacker signs a 6 year contract with a $6 million signing bonus and annual salaries of $4 million prior to the 2002 season. $1 million of his salary is guaranteed every season.
Scenario 1 - Joe is cut April 26th, 2005. The team has already prorated $3 million of his signing bonus ($1 million in each 2002-2004), so that leaves $3 million of signing bonus to count against the 2005 season. Joe also had guaranteed $1 million in 2005, 2006, and 2007 that needs to be accounted for all of which will be immediately felt. That makes the total dead money $6 million ($3 millon left of prorated signing bonus + $1 million guaranteed for 2005 + $1 million for 2006 + $1 million for 2007) felt in 2005.
Scenario 2 - Joe is cut June 2nd, 2005. The team has already prorated $3 million of his signing bonus ($1 million in each 2002-2004), so that leaves $1 million of signing bonus to count against the 2005 season. Joe had guaranteed money of $1 million for 2005, so they must count $2 million for 2005. The remaining $4 million ($2 million left after 2005 in prorated signing bonus + $1 million guaranteed in each 2006 and 2007) in dead money must be counted for by the end of 2006 but can count against either 2005 or 2006.
When we cut Boselli, Scenario 2 occurred (cut after June 1, 2003). We decided, however, to take the full brunt of it in 2003 instead of carrying any of it into 2004.