diff --git a/issue2961002_20001_30001.diff b/issue2961002_20001_30001.diff
new file mode 100644
index 0000000..5f8e4c2
--- /dev/null
+++ b/issue2961002_20001_30001.diff
@@ -0,0 +1,116 @@
+Index: tax.py
+===================================================================
+
+--- ./modules/account/tax.py
++++ ./modules/account/tax.py
+@@ -802,49 +802,52 @@
+ 
+         if self.template:
+             vals = self.template._get_tax_value(tax=self)
+-            if (self.template.invoice_account
+-                    and self.invoice_account.id != template2account.get(
+-                        self.template.invoice_account.id)):
++            if (self.template.invoice_account and (not self.invoice_account
++                        or self.invoice_account.id != template2account.get(
++                            self.template.invoice_account.id))):
+                 vals['invoice_account'] = template2account.get(
+                     self.template.invoice_account.id)
+             elif (not self.template.invoice_account
+                     and self.invoice_account):
+                 vals['invoice_account'] = None
+-            if (self.template.credit_note_account
+-                    and self.credit_note_account.id != template2account.get(
+-                        self.template.credit_note_account.id)):
++            if (self.template.credit_note_account and (not
++                        self.credit_note_account or
++                        self.credit_note_account.id != template2account.get(
++                        self.template.credit_note_account.id))):
+                 vals['credit_note_account'] = template2account.get(
+                     self.template.credit_note_account.id)
+             elif (not self.template.credit_note_account
+                     and self.credit_note_account):
+                 vals['credit_note_account'] = None
+-            if (self.template.invoice_base_code
+-                    and self.invoice_base_code.id != template2tax_code.get(
+-                        self.template.invoice_base_code.id)):
++            if (self.template.invoice_base_code and (not self.invoice_base_code
++                        or self.invoice_base_code.id != template2tax_code.get(
++                            self.template.invoice_base_code.id))):
+                 vals['invoice_base_code'] = template2tax_code.get(
+                     self.template.invoice_base_code.id)
+             elif (not self.template.invoice_base_code
+                     and self.invoice_base_code):
+                 vals['invoice_base_code'] = None
+-            if (self.template.invoice_tax_code
+-                    and self.invoice_tax_code.id != template2tax_code.get(
+-                        self.template.invoice_tax_code.id)):
++            if (self.template.invoice_tax_code and (not self.invoice_tax_code
++                        or self.invoice_tax_code.id != template2tax_code.get(
++                        self.template.invoice_tax_code.id))):
+                 vals['invoice_tax_code'] = template2tax_code.get(
+                     self.template.invoice_tax_code.id)
+             elif (not self.template.invoice_tax_code
+                     and self.invoice_tax_code):
+                 vals['invoice_tax_code'] = None
+-            if (self.template.credit_note_base_code
+-                    and self.credit_note_base_code.id != template2tax_code.get(
+-                        self.template.credit_note_base_code.id)):
++            if (self.template.credit_note_base_code and (not
++                        self.credit_note_base_code or
++                        self.credit_note_base_code.id != template2tax_code.get(
++                        self.template.credit_note_base_code.id))):
+                 vals['credit_note_base_code'] = template2tax_code.get(
+                     self.template.credit_note_base_code.id)
+             elif (not self.template.credit_note_base_code
+                     and self.credit_note_base_code):
+                 vals['credit_note_base_code'] = None
+-            if (self.template.credit_note_tax_code
+-                    and self.credit_note_tax_code.id != template2tax_code.get(
+-                        self.template.credit_note_tax_code.id)):
++            if (self.template.credit_note_tax_code and (not
++                        self.credit_note_tax_code or
++                        self.credit_note_tax_code.id != template2tax_code.get(
++                        self.template.credit_note_tax_code.id))):
+                 vals['credit_note_tax_code'] = template2tax_code.get(
+                     self.template.credit_note_tax_code.id)
+             elif (not self.template.credit_note_tax_code
+@@ -1118,8 +1121,6 @@
+         res = {}
+         if not rule_line or rule_line.group != self.group:
+             res['group'] = self.group.id if self.group else None
+-        if not rule_line or rule_line.origin_tax != self.origin_tax:
+-            res['origin_tax'] = self.origin_tax.id if self.origin_tax else None
+         if not rule_line or rule_line.sequence != self.sequence:
+             res['sequence'] = self.sequence
+         if not rule_line or rule_line.template != self:
+@@ -1271,16 +1272,19 @@
+             vals = self.template._get_tax_rule_line_value(rule_line=self)
+             if self.rule.id != template2rule[self.template.rule.id]:
+                 vals['rule'] = template2rule[self.template.rule.id]
+-            if self.origin_tax:
+-                if self.template.origin_tax:
+-                    if self.origin_tax.id != \
+-                            template2tax[self.template.origin_tax.id]:
+-                        vals['origin_tax'] = template2tax[
+-                            self.template.origin_tax.id]
+-            if self.tax:
+-                if self.template.tax:
+-                    if self.tax.id != template2tax[self.template.tax.id]:
+-                        vals['tax'] = template2tax[self.template.tax.id]
++            if self.template.origin_tax:
++                if (not self.origin_tax or self.origin_tax.id !=
++                        template2tax[self.template.origin_tax.id]):
++                    vals['origin_tax'] = template2tax[
++                        self.template.origin_tax.id]
++            elif self.origin_tax:
++                vals['origin_tax'] = None
++            if self.template.tax:
++                if (not self.tax or self.tax.id !=
++                        template2tax[self.template.tax.id]):
++                    vals['tax'] = template2tax[self.template.tax.id]
++            elif self.tax:
++                vals['tax'] = None
+             if vals:
+                 self.write([self], vals)
+             template2rule_line[self.template.id] = self.id
+
diff --git a/series b/series
index 0d90cd5..b4643f2 100644
--- a/series
+++ b/series
@@ -10,3 +10,4 @@ add_db_client.diff
 issue2661002_20001.diff
 issue101_226.diff
 issue2731002_20001.diff
+issue2961002_20001_30001.diff