Don't use identity records in SQL server but that's another story. You don't pass a value to the identity field, SQL server does.

You could find out what SQL server is going to set the value to by

select max(identityFld) from table

Just add the increment to the retrieved value. If you don't know (in this case you do) what the increment value is you can use the function "ident_incr" to determine it.