This page:
http://www.meetup.com/Grilli/boards/thread/4679227/30/?pager...
shows:
"Addizionale Regionale Comp. rata = -20,68
Addizionale Regionale Agg. rata = -11,49
Acconto Addizionale Comunale Agg. rata = -3,83
Addizionale Comunale Agg. rata = -9,34
Totale = -45,34 euro."
I ask: what's the difference between "... comp. rata" and "... agg. rata"?
"Agg." is aggiornamento, I believe.
It seems that you had already a previous balance of additional regional tax due and you then updated the value and added the additional municipal tax.
So, "comp." would be something like "previous balance"?
And "rata" would be "payment" or "installment" or could also be translated as "due"?
The translation workplace 
