First round of tax code replacement, adds cumulative tax support

git-svn-id: https://ledger-smb.svn.sourceforge.net/svnroot/ledger-smb/trunk@195 4979c152-3d1c-0410-bac9-87ea11338e46

7 files changed, 301 insertions, 180 deletions

diff --git a/LedgerSMB/AM.pm b/LedgerSMB/AM.pm
index c1576aed..82b58534 100755
--- a/LedgerSMB/AM.pm
+++ b/LedgerSMB/AM.pm
@@ -35,7 +35,7 @@
 #======================================================================
 
 package AM;
-
+use LedgerSMB::Tax;
 
 sub get_account {
 
@@ -1479,15 +1479,18 @@ sub defaultaccounts {
 sub taxes {
 
 	my ($self, $myconfig, $form) = @_;
+	my $taxaccounts = '';
 
 	# connect to database
 	my $dbh = $form->{dbh};
 
 	my $query = qq|
-		  SELECT c.id, c.accno, c.description,
-		         t.rate * 100 AS rate, t.taxnumber, t.validto
+		  SELECT c.id, c.accno, c.description, 
+		         t.rate * 100 AS rate, t.taxnumber, t.validto,
+			 t.pass, m.taxmodulename
 		    FROM chart c
 		    JOIN tax t ON (c.id = t.chart_id)
+		    JOIN taxmodule m ON (t.taxmodule_id = m.taxmodule_id)
 		ORDER BY 3, 6|;
 
 	my $sth = $dbh->prepare($query);
@@ -1495,6 +1498,21 @@ sub taxes {
 
 	while (my $ref = $sth->fetchrow_hashref(NAME_lc)) {
 		push @{ $form->{taxrates} }, $ref;
+		$taxaccounts .= " " . $ref{accno};
+	}
+
+	$sth->finish;
+	
+	$query = qq|
+		SELECT taxmodule_id, taxmodulename FROM taxmodule
+		ORDER BY 2|;
+	
+	$sth = $dbh->prepare($query);
+	$sth->execute || $form->dberror($query);
+
+	while (my $ref = $sth->fetchrow_hashref(NAME_lc)) {
+		$form->{"taxmodule_".$ref->{taxmodule_id}} = 
+			$ref->{taxmodulename};
 	}
 
 	$sth->finish;
@@ -1516,16 +1534,20 @@ sub save_taxes {
 
 
 	$query = qq|
-		INSERT INTO tax (chart_id, rate, taxnumber, validto)
-		     VALUES (?, ?, ?, ?)|;
+		INSERT INTO tax (chart_id, rate, taxnumber, validto, 
+			pass, taxmodule_id)
+			VALUES (?, ?, ?, ?, ?, ?)|;
 
 	my $sth = $dbh->prepare($query);
 	foreach my $item (split / /, $form->{taxaccounts}) {
 		my ($chart_id, $i) = split /_/, $item;
 		my $rate = $form->parse_amount(
 			$myconfig, $form->{"taxrate_$i"}) / 100;
+		my $validto = $form->{"validto_$i"};
+		$validto = undef if not $validto;
 		my @queryargs = ($chart_id, $rate, $form->{"taxnumber_$i"},
-			$form->{"validto_$i"});
+			$validto, $form->{"pass_$i"},
+			$form->{"taxmodule_id_$i"});
 
 		$sth->execute(@queryargs) || $form->dberror($query);
 	}
diff --git a/LedgerSMB/Form.pm b/LedgerSMB/Form.pm
index cd30803b..e5fa4f61 100755
--- a/LedgerSMB/Form.pm
+++ b/LedgerSMB/Form.pm
@@ -1579,7 +1579,7 @@ sub check_exchangerate {
 
 	my $sth = $self->{dbh}->prepare($query);
 	$sth->execute($currenct, $transdate);
-	my ($exchangerate) = $sth->fetchrow_array($query);
+	my ($exchangerate) = $sth->fetchrow_array;
 
 	$sth->finish;
 	$self->{dbh}->commit;
diff --git a/LedgerSMB/IR.pm b/LedgerSMB/IR.pm
index 92e2c964..9f2da830 100755
--- a/LedgerSMB/IR.pm
+++ b/LedgerSMB/IR.pm
@@ -32,6 +32,7 @@
 #======================================================================
 
 package IR;
+use LedgerSMB::Tax;
 use LedgerSMB::PriceMatrix;
 
 sub post_invoice {
@@ -172,33 +173,24 @@ sub post_invoice {
       my $linetotal = $form->round_amount($amount, 2);
       $fxdiff += $amount - $linetotal;
 
-      @taxaccounts = split / /, $form->{"taxaccounts_$i"};
+      @taxaccounts = Tax::init_taxes($form, $form->{"taxaccounts_$i"});
 
-      $ml = 1;
-      $tax = 0;
-      $fxtax = 0;
+      $tax = Math::BigFloat->bzero();
+      $fxtax = Math::BigFloat->bzero();
       
-      for (0 .. 1) {
-	$taxrate = 0;
-	
-        # add tax rates
-	for (@taxaccounts) {
-	  $taxrate += $form->{"${_}_rate"} if ($form->{"${_}_rate"} * $ml) > 0;
-	}
-
-	if ($form->{taxincluded}) {
-	  $tax += $amount = $linetotal * ($taxrate / (1 + ($taxrate * $ml)));
-	  $form->{"sellprice_$i"} -= $amount / $form->{"qty_$i"};
-	} else {
-	  $tax += $amount = $linetotal * $taxrate;
-	  $fxtax += $fxlinetotal * $taxrate;
-	}
-
-        for (@taxaccounts) {
-	  $form->{acc_trans}{$form->{id}}{$_}{amount} += $amount * $form->{"${_}_rate"} / $taxrate if ($form->{"${_}_rate"} * $ml) > 0;
-	}
-	
-	$ml = -1;
+      if ($form->{taxincluded}) {
+        $tax += $amount = Tax::calculate_taxes(\@taxaccounts, $form, 
+	  $linetotal, 1);
+	$form->{"sellprice_$i"} -= $amount / $form{"qty_$i"};
+      } else {
+        $tax += $amount = Tax::calculate_taxes(\@taxaccounts, $form,
+	  $linetotal, 0);
+	$fxtax += Tax::calculate_taxes(\@taxaccounts, $form, 
+	  $fxlinetotal, 0);
+      }
+      
+      for (@taxaccounts) {
+	$form->{acc_trans}{$form->{id}}{$_->account}{amount} += $_->value;
       }
 
       $grossamount = $form->round_amount($linetotal, 2);
diff --git a/LedgerSMB/IS.pm b/LedgerSMB/IS.pm
index eda3a984..0b38b3a8 100755
--- a/LedgerSMB/IS.pm
+++ b/LedgerSMB/IS.pm
@@ -32,6 +32,7 @@
 #======================================================================
 
 package IS;
+use LedgerSMB::Tax;
 use LedgerSMB::PriceMatrix;
 
 sub invoice_details {
@@ -263,44 +264,30 @@ sub invoice_details {
       $form->{"linetotal_$i"} = $form->format_amount($myconfig, $linetotal, 2);
       push(@{ $form->{linetotal} }, $form->{"linetotal_$i"});
       
-      @taxaccounts = split / /, $form->{"taxaccounts_$i"};
+      @taxaccounts = Tax::init_taxes($form, $form->{"taxaccounts_$i"});
       
       my $ml = 1;
       my @taxrates = ();
       
       $tax = 0;
       
-      for (0 .. 1) {
-	$taxrate = 0;
-	
-	for (@taxaccounts) { $taxrate += $form->{"${_}_rate"} if ($form->{"${_}_rate"} * $ml) > 0 }
-	
-	$taxrate *= $ml;
-	$taxamount = $linetotal * $taxrate / (1 + $taxrate);
-	$taxbase = ($linetotal - $taxamount);
-
-	foreach $item (@taxaccounts) {
-	  if (($form->{"${item}_rate"} * $ml) > 0) {
-	    
-	    push @taxrates, $form->{"${item}_rate"} * 100;
-	    
-	    if ($form->{taxincluded}) {
-	      $taxaccounts{$item} += $linetotal * $form->{"${item}_rate"} / (1 + $taxrate);
-	      $taxbase{$item} += $taxbase;
-	    } else {
-	      $taxbase{$item} += $linetotal;
-	      $taxaccounts{$item} += $linetotal * $form->{"${item}_rate"};
-	    }
-	  }
-	}
+      if ($form->{taxincluded}) {
+        $taxamount = Tax::calculate_taxes(\@taxaccounts, $form, $linetotal, 1);
+        $taxbase = ($linetotal - $taxamount);
+	$tax += Tax::extract_taxes(\@taxaccounts, $form, $linetotal);
+      } else {
+        $taxamount = Tax::calculate_taxes(\@taxaccounts, $form, $linetotal, 0);
+	$tax += Tax::apply_taxes(\@taxaccounts, $form, $linetotal);
+      }
 
+      foreach $item (@taxaccounts) {
+        push @taxrates, 100 * $item->rate;
+	$taxaccounts{$item->account} += $item->value;
 	if ($form->{taxincluded}) {
-	  $tax += $linetotal * ($taxrate / (1 + ($taxrate * $ml)));
+	  $taxbase{$item->account} += $taxbase;
 	} else {
-	  $tax += $linetotal * $taxrate;
+	  $taxbase{$item->account} += $linetotal;
 	}
-	
-	$ml *= -1;
       }
 
       push(@{ $form->{lineitems} }, { amount => $linetotal, tax => $form->round_amount($tax, 2) });
@@ -699,31 +686,20 @@ sub post_invoice {
       my $linetotal = $form->round_amount($amount, 2);
       $fxdiff += $amount - $linetotal;
       
-      @taxaccounts = split / /, $form->{"taxaccounts_$i"};
+      @taxaccounts = Tax::init_taxes($form, $form->{"taxaccounts_$i"});
       $ml = 1;
       $tax = 0;
       $fxtax = 0;
       
-      for (0 .. 1) {
-	$taxrate = 0;
-
-	# add tax rates
-	for (@taxaccounts) { $taxrate += $form->{"${_}_rate"} if ($form->{"${_}_rate"} * $ml) > 0 }
-
-	if ($form->{taxincluded}) {
-	  $tax += $amount = $linetotal * ($taxrate / (1 + ($taxrate * $ml)));
-	  $form->{"sellprice_$i"} -= $amount / $form->{"qty_$i"};
-	  $fxtax += $fxlinetotal * ($taxrate / (1 + ($taxrate * $ml)));
-	} else {
-	  $tax += $amount = $linetotal * $taxrate;
-	  $fxtax += $fxlinetotal * $taxrate;
-	}
-
-        for (@taxaccounts) {
-	  $form->{acc_trans}{$form->{id}}{$_}{amount} += $amount * $form->{"${_}_rate"} / $taxrate if ($form->{"${_}_rate"} * $ml) > 0;
-	}
-	
-	$ml = -1;
+      if ($form->{taxincluded}) {
+        $tax += $amount = Tax::calculate_taxes(\@taxaccounts, $form,
+		$linetotal, 1);
+	$form->{"sellprice_$i"} -= $amount / $form->{"qty_$i"};
+	$fxtax += Tax::calculate_taxes(\@taxaccounts, $form, $linetotal, 1);
+      } else {
+        $tax += $amount = Tax::calculate_taxes(\@taxaccounts, $form,
+		$linetotal, 0);
+	$fxtax += Tax::calculate_taxes(\@taxaccounts, $form, $linetotal, 0);
       }
 
       $grossamount = $form->round_amount($linetotal, 2);
@@ -832,7 +808,11 @@ sub post_invoice {
   $invnetamount = $amount;
   
   $amount = 0;
-  for (split / /, $form->{taxaccounts}) { $amount += $form->{acc_trans}{$form->{id}}{$_}{amount} = $form->round_amount($form->{acc_trans}{$form->{id}}{$_}{amount}, 2) }
+  for (split / /, $form->{taxaccounts}) { 
+    $amount += 
+      $form->{acc_trans}{$form->{id}}{$_}{amount} = 
+      $form->round_amount($form->{acc_trans}{$form->{id}}{$_}{amount}, 2); 
+  }
   $invamount = $invnetamount + $amount;
 
   $diff = 0;
diff --git a/LedgerSMB/OE.pm b/LedgerSMB/OE.pm
index 9ebbad19..0d9ab99d 100755
--- a/LedgerSMB/OE.pm
+++ b/LedgerSMB/OE.pm
@@ -33,7 +33,7 @@
 #======================================================================
 
 package OE;
-
+use LedgerSMB::Tax;
 
 sub transactions {
 	my ($self, $myconfig, $form) = @_;
@@ -419,67 +419,52 @@ sub save {
 				$form->{"sellprice_$i"} * $form->{"qty_$i"}, 2
 			);
       
-			@taxaccounts = split / /, $form->{"taxaccounts_$i"};
-			$taxrate = 0;
-			$taxdiff = 0;
-      
-			for (@taxaccounts) { $taxrate += $form->{"${_}_rate"} }
-
+			@taxaccounts = Tax::init_taxes($form,
+				$form->{"taxaccounts_$i"});
 			if ($form->{taxincluded}) {
-				$taxamount = $linetotal * $taxrate 
-					/ (1 + $taxrate);
-				$taxbase = $linetotal - $taxamount;
-				# we are not keeping a natural price, 
-				# do not round
-				$form->{"sellprice_$i"} = 
-					$form->{"sellprice_$i"} 
-						* (1 / (1 + $taxrate));
+				$taxamount = Tax::calculate_taxes(\@taxaccounts,
+					$form, $linetotal, 1);
+				$form->{"sellprice_$i"} = Tax::extract_taxes(\@taxaccounts,
+					$form, $form->{"sellprice_$i"});
+				$taxbase = Tax::extract_taxes(\@taxaccounts, 
+					$form, $linetotal);
 			} else {
-				$taxamount = $linetotal * $taxrate;
+				$taxamount = Tax::apply_taxes(\@taxaccounts,
+					$form, $linetotal);
 				$taxbase = $linetotal;
 			}
-
-			if (@taxaccounts && $form->round_amount($taxamount, 2) 
-					== 0) {
-				if ($form->{taxincluded}) {
+ 
+ 			if (@taxaccounts && $form->round_amount($taxamount, 2) 
+ 					== 0) {
+ 				if ($form->{taxincluded}) {
 					foreach $item (@taxaccounts) {
 						$taxamount = 
 							$form->round_amount(
-
-							$linetotal 
-							* $form->{"${item}_rate"} 
-							/ (1 + abs(
-								$form->{"${item}_rate"}
-							)), 2
-						);
-
-						$taxaccounts{$item} += 
+							$item->value, 2);
+						$taxaccounts{$item->account} +=
 							$taxamount;
-						$taxdiff += $taxamount; 
-
-						$taxbase{$item} += $taxbase;
+						$taxdiff += $taxamount;
+						$taxbase{$item->account} +=
+							$taxbase;
 					}
-					$taxaccounts{$taxaccounts[0]} 
+					$taxaccounts{$taxaccounts[0]->account} 
 						+= $taxdiff;
-				} else {
+ 				} else {
 					foreach $item (@taxaccounts) {
-						$taxaccounts{$item} += 
-							$linetotal * 
-							$form->{"${item}_rate"};
-						$taxbase{$item} += $taxbase;
+						$taxaccounts{$item->account} +=
+							$item->value;
+						$taxbase{$item->account} +=
+							$taxbase;
 					}
 				}
 			} else {
 				foreach $item (@taxaccounts) {
-					$taxaccounts{$item} += 
-						$taxamount * 
-						$form->{"${item}_rate"} / 
-						$taxrate;
-					$taxbase{$item} += $taxbase;
+					$taxaccounts{$item->account} += 
+						$item->value;
+					$taxbase{$item->account} += $taxbase;
 				}
 			}
 
-
 			$netamount += $form->{"sellprice_$i"} 
 				* $form->{"qty_$i"};
       
@@ -939,7 +924,7 @@ sub retrieve {
 		$sth->finish;
 
 		# get recurring transaction
-		$form->get_recurring($dbh);
+		$form->get_recurring;
 
 		@queries = $form->run_custom_queries('oe', 'SELECT');
 		$form->{dbh}->commit;
@@ -1328,66 +1313,39 @@ sub order_details {
 				$myconfig, $linetotal, 2);
 			push(@{ $form->{linetotal} }, $form->{"linetotal_$i"});
       
-			@taxaccounts = split / /, $form->{"taxaccounts_$i"};
+			@taxaccounts = Tax::init_taxes($form, 
+				$form->{"taxaccounts_$i"});
 
 			my $ml = 1;
 			my @taxrates = ();
       
 			$tax = 0;
       
-			for (0 .. 1) {
-				$taxrate = 0;
-
-				for (@taxaccounts) { 
-					$taxrate += $form->{"${_}_rate"} 
-						if ($form->{"${_}_rate"} * $ml) 
-							> 0; 
-				}
-	
-				$taxrate *= $ml;
-				$taxamount = $linetotal * $taxrate 
-					/ (1 + $taxrate);
-				$taxbase = ($linetotal - $taxamount);
-	
-				foreach $item (@taxaccounts) {
-					if (($form->{"${item}_rate"} * $ml) 
-								> 0) {
-
-						push @taxrates, 
-							$form->{"${item}_rate"} 
-								* 100;
-	    
-						if ($form->{taxincluded}) {
-
-							$taxaccounts{$item}
-								+= $linetotal 
-								* $form->{"${item}_rate"} 
-								/ 
-								(1 + $taxrate);
-
-							$taxbase{$item} 
-								+= $taxbase;
-						} else {
-							$taxbase{$item} 
-								+= $linetotal;
-
-							$taxaccounts{$item} 
-								+= $linetotal 
-								* $form->{"${item}_rate"};
-
-						}
-					}
-				}
-
+			$taxamount = Tax::calculate_taxes(\@taxaccounts,
+				$form, $linetotal, 1);
+			$taxbase = Tax::extract_taxes(\@taxaccounts,
+				$form, $linetotal);
+			foreach $item (@taxaccounts) {
+				push @taxrates, Math::BigFloat->new(100) *
+					$item->rate;
 				if ($form->{taxincluded}) {
-					$tax += $linetotal 
-						* ($taxrate 
-						/ (1 + ($taxrate * $ml)));
+					$taxaccounts{$item->account} += 
+						$item->value;
+					$taxbase{$item->account} += $taxbase;
 				} else {
-					$tax += $linetotal * $taxrate;
+					Tax::apply_taxes(\@taxaccounts, $form,
+						$linetotal);
+					$taxbase{$item->account} += $linetotal;
+					$taxaccounts{$item->account} += 
+						$item->value;
 				}
-	
-				$ml *= -1;
+			}
+			if ($form->{taxincluded}) {
+				$tax += Tax::calculate_taxes(\@taxaccounts,
+					$form, $linetotal, 1);
+			} else {
+				$tax += Tax::calculate_taxes(\@taxaccounts, 
+					$form, $linetotal, 0);
 			}
 
 			push(@{ $form->{lineitems} }, 
@@ -2422,19 +2380,24 @@ sub generate_orders {
 			$sth->execute($parts_id) || $form->dberror($query);
       
 			my $rate = 0;
+			my $taxes = '';
 			while ($ref = $sth->fetchrow_hashref(NAME_lc)) {
 				$description = $ref->{description};
 				$unit = $ref->{unit};
 				$rate += $tax{$ref->{accno}};
+				$taxes .= "$ref->{accno} ";
 			}
- 			$sth->finish;  
+ 			$sth->finish;
+			chop $taxes;
+			my @taxaccounts = Tax::init_taxes($form, $taxes);
 
 			$netamount += $linetotal;
 			if ($taxincluded) {
 				$amount += $linetotal;
 			} else {
 				$amount += $form->round_amount(
-					$linetotal * (1 + $rate), 2);
+					Tax::apply_taxes(\@taxaccounts, $form,
+					$linetotal), 2);
 			}
 	
       
diff --git a/LedgerSMB/Tax.pm b/LedgerSMB/Tax.pm
new file mode 100755
index 00000000..4c7bd121
--- /dev/null
+++ b/LedgerSMB/Tax.pm
@@ -0,0 +1,100 @@
+#=====================================================================
+#
+# Tax support module for LedgerSMB
+# LedgerSMB::Tax
+#  Default simple tax application
+#
+# LedgerSMB 
+# Small Medium Business Accounting software
+# http://www.ledgersmb.org/
+# 
+#
+# Copyright (C) 2006
+# This work contains copyrighted information from a number of sources all used
+# with permission.  It is released under the GNU General Public License 
+# Version 2 or, at your option, any later version.  See COPYRIGHT file for 
+# details.
+#
+#
+#======================================================================
+# This package contains tax related functions:
+#
+# apply_taxes - applies taxes to the given subtotal
+# extract_taxes - extracts taxes from the given total
+# initialize_taxes - loads taxes from the database
+# calculate_taxes - calculates taxes
+#
+#====================================================================
+package Tax;
+
+use Math::BigFloat;
+
+sub init_taxes {
+	my ($form, $taxaccounts) = @_;
+	my $dbh = $form->{dbh};
+	@taxes = ();
+	my @accounts = split / /, $taxaccounts;
+	my $query = qq|SELECT t.taxnumber, c.description,
+			t.rate, t.chart_id, t.pass, m.taxmodulename
+			FROM tax t INNER JOIN chart c ON (t.chart_id = c.id)
+			INNER JOIN taxmodule m ON (t.taxmodule_id = m.taxmodule_id)
+			WHERE c.accno = ?|;
+	my $sth = $dbh->prepare($query);
+	foreach $taxaccount (@accounts) {
+		$sth->execute(int($taxaccount)) || $form->dberror($query);
+		my $ref = $sth->fetchrow_hashref;
+
+		my $module = $ref->{'taxmodulename'};
+		require "LedgerSMB/Taxes/${module}.pm";
+		$module =~ s/\//::/g;
+		my $tax = (eval 'Taxes::'.$module)->new();
+
+		$tax->pass($ref->{'pass'});
+		$tax->account($taxaccount);
+		$tax->rate(Math::BigFloat->new($ref->{'rate'}));
+		$tax->taxnumber($ref->{'taxnumber'});
+		$tax->chart($ref->{'chart'});
+		$tax->description($ref->{'description'});
+		$tax->value(Math::BigFloat->bzero());
+
+		push @taxes, $tax;
+		$sth->finish;
+	}
+	return @taxes;
+}
+
+sub calculate_taxes {
+	my ($taxes, $form, $subtotal, $extract) = @_;
+	my $total = Math::BigFloat->bzero();
+	my %passes;
+	foreach my $tax (@taxes) {
+		push @{$passes{$tax->pass}}, $tax;
+	}
+	my @passkeys = sort keys %passes;
+	@passkeys = reverse @passkeys if $extract;
+	foreach my $pass (@passkeys) {
+		my $passrate = Math::BigFloat->bzero();
+		my $passtotal = Math::BigFloat->bzero();
+		foreach my $tax (@{$passes{$pass}}) {
+			$passrate += $tax->rate;
+		}
+		foreach my $tax (@{$passes{$pass}}) {
+			$passtotal += $tax->apply_tax($form, $subtotal + $total) if not $extract;
+			$passtotal += $tax->extract_tax($form, $subtotal - $total, $passrate) if $extract;
+		}
+		$total += $passtotal;
+	}
+	return $total;
+}
+
+sub apply_taxes {
+	my ($taxes, $form, $subtotal) = @_;
+	return $subtotal + calculate_taxes($taxes, $form, $subtotal, 0);
+}
+
+sub extract_taxes {
+	my ($taxes, $form, $subtotal) = @_;
+	return $subtotal - calculate_taxes($taxes, $form, $subtotal, 1);
+}
+
+1;
diff --git a/LedgerSMB/Taxes/Simple.pm b/LedgerSMB/Taxes/Simple.pm
new file mode 100755
index 00000000..57777be4
--- /dev/null
+++ b/LedgerSMB/Taxes/Simple.pm
@@ -0,0 +1,64 @@
+#=====================================================================
+#
+# Simple Tax support module for LedgerSMB
+# Taxes::Simple
+#  Default simple tax application
+#
+# LedgerSMB 
+# Small Medium Business Accounting software
+# http://www.ledgersmb.org/
+# 
+#
+# Copyright (C) 2006
+# This work contains copyrighted information from a number of sources all used
+# with permission.  It is released under the GNU General Public License 
+# Version 2 or, at your option, any later version.  See COPYRIGHT file for 
+# details.
+#
+#
+#======================================================================
+# This package contains tax related functions:
+#
+# calculate_tax - calculates tax on subtotal
+# apply_tax - sets $value to the tax value for the subtotal
+# extract_tax - sets $value to the tax value on a tax-included subtotal
+#
+#====================================================================
+package Taxes::Simple;
+
+use Class::Struct;
+use Math::BigFloat;
+
+struct Taxes::Simple => {
+	taxnumber => '$',
+	description => '$',
+	rate => 'Math::BigFloat',
+	chart => '$',
+	account => '$',
+	value => 'Math::BigFloat',
+	pass => '$'
+};
+
+sub calculate_tax {
+	my ($self, $form, $subtotal, $extract, $passrate) = @_;
+	my $rate = $self->rate;
+	my $tax = $subtotal * $rate / (Math::BigFloat->bone() + $passrate);
+	$tax = $subtotal * $rate if not $extract;
+	return $tax;
+}
+
+sub apply_tax {
+	my ($self, $form, $subtotal) = @_;
+	my $tax = $self->calculate_tax($form, $subtotal, 0);
+	$self->value($tax);
+	return $tax;
+}
+
+sub extract_tax {
+	my ($self, $form, $subtotal, $passrate) = @_;
+	my $tax = $self->calculate_tax($form, $subtotal, 1, $passrate);
+	$self->value($tax);
+	return $tax;
+}
+
+1;