diff --git a/src/cg/cg4301.cpp b/src/cg/cg4301.cpp
index 1a0adccbe..1339f5374 100755
--- a/src/cg/cg4301.cpp
+++ b/src/cg/cg4301.cpp
@@ -2913,11 +2913,11 @@ void TLiquidazione_app::recalc_att(int month, const char* codatt, TAssoc_array &
       
       // Somma i vari prorata calcolati per gli anni precedenti
       prorata += prorata_precedente1 + prorata_precedente2;
-
-      acquisti_iva -= prorata; // Rettifica acquisti_iva
-
-      prorata += prorata_diff;        
-      fdiffinc_iva_acq -= prorata_diff; // Rettifica acquisti_iva differiti incassati
+			prorata += prorata_diff;
+			if (!lia.get_bool("B7"))
+				prorata =  ZERO;
+			acquisti_iva -= prorata; // Rettifica acquisti_iva
+			fdiffinc_iva_acq -= prorata_diff; // Rettifica acquisti_iva differiti incassati
     }
     look_plm(month, codatt, true);   
     
@@ -4256,7 +4256,7 @@ void TLiquidazione_app::write_liq(int month, const char* codatts)
         }
         
         // calcolo conguaglio -- se positivo e' a debito
-        if (prorata > ZERO)
+        if (prorata > ZERO && lia.get_bool("B7"))
         {
           topay = (iaq + ppg) * prorata / CENTO; 
           round_imposta(topay);
diff --git a/src/cg/cg4304.cpp b/src/cg/cg4304.cpp
index 178473231..d92871195 100755
--- a/src/cg/cg4304.cpp
+++ b/src/cg/cg4304.cpp
@@ -2028,28 +2028,35 @@ void TLiquidazione_app::set_pumpam(const _DescrItem& d)
     real rprc = CENTO - prc;
     TString ss(rprc.string());
 
-    set_row(row++, FR("%% PRO-RATA (%s%%) ed IVA non detraibile (%s%%)@69g%r"), 
-            (const char*) ss, (const char*)prc.string(), &(d._r11));
-    yy-=2;
-    if (d._r13 != INVALID_PRORATA && d._r12 != ZERO)
-    {
-      rprc = CENTO - d._r13;
-      ss = rprc.string();
-      set_row(row++, FR("%% PRO-RATA %d (%s%%) ed IVA non detraibile (%s%%)@69g%r"), 
-              yy, (const char*) ss, (const char*)d._r13.string(), &(d._r12));
-    }
+		if (d._r11 != ZERO)
+			set_row(row++, FR("%% PRO-RATA (%s%%) ed IVA non detraibile (%s%%)@69g%r"),
+				(const char*)ss, (const char*)prc.string(), &(d._r11));
+		else
+			set_row(row++, FR("%% PRO-RATA (%s%%)"), (const char*)ss);
+		yy-=2;
+    if (d._r13 != INVALID_PRORATA)
+		{
+			rprc = CENTO - d._r13;
+			ss = rprc.string();
+			if (d._r12 != ZERO)
+				set_row(row++, FR("%% PRO-RATA %d (%s%%) ed IVA non detraibile (%s%%)@69g%r"), yy, (const char*)ss, (const char*)d._r13.string(), &(d._r12));
+			else
+				set_row(row++, FR("%% PRO-RATA %d (%s%%)"), yy, (const char*)ss);
+		}
     else
       if (!_isfinal && d._r13 == INVALID_PRORATA_ASSERT) 
         set_row(row++, FR("Impossibile reperire la %% PRO-RATA relativa all'anno %d."), yy);
 
     yy--;
-    if (d._r15 != INVALID_PRORATA && d._r14 != ZERO)
-    {
-      rprc = CENTO - d._r15;
-      ss = rprc.string();
-      set_row(row++, FR("%% PRO-RATA %d (%s%%) ed IVA non detraibile (%s%%)@69g%r"), 
-              yy, (const char*) ss, (const char*)d._r15.string(), &(d._r14));
-    }
+    if (d._r15 != INVALID_PRORATA)
+		{
+			rprc = CENTO - d._r15;
+			ss = rprc.string();
+			if (d._r14 != ZERO)
+				set_row(row++, FR("%% PRO-RATA %d (%s%%) ed IVA non detraibile (%s%%)@69g%r"), yy, (const char*) ss, (const char*)d._r15.string(), &(d._r14));
+			else
+				set_row(row++, FR("%% PRO-RATA %d (%s%%)"), yy, (const char*)ss);
+		}
     else
       if (!_isfinal && d._r15 == INVALID_PRORATA_ASSERT) 
         set_row(row++, FR("Impossibile reperire la %% PRO-RATA relativa all'anno %d."), yy);
@@ -2814,8 +2821,10 @@ bool TLiquidazione_app::set_annual(_DescrItem& d)
 		const real rev_charge = d._r18;
     const TString16 s1 = perc_det.stringa();
     const TString16 s2 = d._r2.stringa();
-    set_row(row++, FR("%% PRO-RATA (%s%%) ed IVA non detraibile (%s%%)@69g%r"), 
-            (const char*)s1, (const char*)s2, &(d._r6));                     
+		if (d._r6 > ZERO)
+			set_row(row++, FR("%% PRO-RATA (%s%%) ed IVA non detraibile (%s%%)@69g%r"), (const char*)s1, (const char*)s2, &(d._r6));
+		else
+			set_row(row++, FR("%% PRO-RATA (%s%%)"), (const char*)s1);
 		const real denom = vol_aff - rev_charge;
 		const real num = denom - d._r1 - d._r4 - d._r5 + d._r8 - d._r7 + d._r9;
 		set_row(row++, FR("Numeratore pro-rata                                        @69g%r"), &num);
diff --git a/src/cg/cg5300a.h b/src/cg/cg5300a.h
index a464d3bba..8a613df71 100755
--- a/src/cg/cg5300a.h
+++ b/src/cg/cg5300a.h
@@ -19,6 +19,7 @@
 #define F_GESMANCRED  219
 #define F_RCDAL       223
 #define F_RCAL        224
+#define F_PRORATA			225
 
 #define F_ROUNDLIQ    221  
 #define F_ROUNDDIC    222
diff --git a/src/cg/cg5300a.uml b/src/cg/cg5300a.uml
index 00a9f5d29..ecd184ca2 100755
--- a/src/cg/cg5300a.uml
+++ b/src/cg/cg5300a.uml
@@ -151,6 +151,12 @@ BEGIN
   FIELD B6
 END
 
+BOOLEAN F_PRORATA
+BEGIN
+  PROMPT 50 9 "Calcolo Pro rata"
+  FIELD B7
+END
+
 GROUPBOX DLG_NULL 78 6
 BEGIN
   PROMPT 1 11 "@bCredito"