taxes/tax_calc.inc

   1 <?php
   2 /**********************************************************************
   3     Copyright (C) FrontAccounting, LLC.
   4         Released under the terms of the GNU General Public License, GPL,
   5         as published by the Free Software Foundation, either version 3
   6         of the License, or (at your option) any later version.
   7     This program is distributed in the hope that it will be useful,
   8     but WITHOUT ANY WARRANTY; without even the implied warranty of
   9     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  10     See the License here <http://www.gnu.org/licenses/gpl-3.0.html>.
  11 ***********************************************************************/
  12 include_once($path_to_root . "/taxes/db/tax_groups_db.inc");
  13 include_once($path_to_root . "/taxes/db/tax_types_db.inc");
  14 include_once($path_to_root . "/taxes/db/item_tax_types_db.inc");
  15
  16 //---------------------------------------------------------------------------------
  17 // Returns basic fiscal parameters for transaction item which depend on stock type and customer/supplier tax area.
  18 //
  19 // vat_category => stock tax category
  20 // tax_area => cust/supp tax area
  21 // taxes => all taxes applicable:
  22 //      tax_type_id1 => (tax_type_id, tax_type_name, sales_gl_code, purchasing_gl_code, rate)
  23 //      tax_type_id2 => ...
  24
  25 function get_base_taxdata($stock_id, $group_id)
  26 {
  27         static $last_group = null, $group_data;
  28
  29         if ($last_group != $group_id) { // cache group data for better performance
  30                 $last_group = $group_id;
  31                 $group_data = get_tax_group_data($group_id);
  32         }
  33
  34         $taxdata = array('tax_area' => $group_data['tax_area'], 'taxes' => null);
  35
  36         if ($stock_id===null) // shipping special case
  37         {
  38                 $taxdata['vat_category'] = VC_SERVICES;
  39                 $taxdata['taxes'] = get_tax_group_items_as_array(null);
  40                 return $taxdata;
  41         }
  42
  43         $item_tax_type = get_item_tax_type_for_item($stock_id); // get item tax data
  44         $taxdata['vat_category'] = $item_tax_type['vat_category'];
  45
  46         // if the item is exempt from all taxes thats all
  47         if ($item_tax_type["exempt"])
  48                 return $taxdata;
  49
  50         $taxdata['taxes'] = array();
  51
  52         // get the exemptions for this item tax type
  53         $item_tax_type_exemptions_db = get_item_tax_type_exemptions($item_tax_type["id"]);
  54
  55         // read them all into an array to minimize db querying
  56         $item_tax_type_exemptions = array();
  57         while ($item_tax_type_exemp = db_fetch($item_tax_type_exemptions_db))
  58         {
  59                 $item_tax_type_exemptions[] = $item_tax_type_exemp["tax_type_id"];
  60         }
  61
  62         $tax_group_items_array = $group_data['taxes'];
  63         // if any of the taxes of the tax group are in the exemptions, then skip
  64         foreach ($tax_group_items_array as $tax_group_item)
  65         {
  66
  67                 $skip = false;
  68
  69                 // if it's in the exemptions, skip
  70                 if (is_null($tax_group_item['rate']))
  71                         $skip = true;
  72                 else
  73                         foreach ($item_tax_type_exemptions as $exemption)
  74                         {
  75                                 if (($tax_group_item['tax_type_id'] == $exemption))
  76                                 {
  77                                 $skip = true;
  78                                 break;
  79                                 }
  80                         }
  81
  82                 if (!$skip)
  83                 {
  84                         $index = $tax_group_item['tax_type_id'];
  85                         $taxdata['taxes'][$index] = $tax_group_item;
  86                 }
  87         }
  88
  89         return $taxdata;
  90 }
  91
  92 /*
  93         Main tax procedure splitting transaction item value according to item tax rules applicable:
  94                 $stock_id - stock item code; special case is '' for shipping
  95                 $amount - price/value to be splitted
  96                 $tax_group - entity tax group
  97                 $tax_included - whether value includes all taxes
  98                 $vat_factor - 0-1; tax deduction factor
  99                 $allow_reverse - option for invoice - whether to honour reverse charging
 100
 101         Returned array contains calculated values for GL postings and tax registration:
 102                 'Net' - value without tax,
 103                 'Tax' - tax sum,
 104                 'Cost' - cost value (can be higher then Net value),
 105                 'vat_category' -  stock tax category
 106
 107         and (with numeric keys) detailed info for any applicable tax rate:
 108                 'tax_type_id' - tax type id
 109                 'Value' - charged tax value
 110                 'Deductible' - tax deductible (can be lower than Value for special goods)
 111                 'Payable' - tax payable
 112                 'Adjust' - additional adjustemnt to deductible tax due to sales structure factor
 113                 'rate' - tax rate
 114                 'sales_gl_code' - sales tax GL account
 115                 'purchasing_gl_code' - purchase tax GL account
 116                 'tax_type_name' - name of tax type
 117 */
 118 function split_item_price($stock_id, $amount, $group_id, $tax_included=false, $trans_type=ST_SUPPINVOICE, $vat_factor = 1,
 119         $allow_reverse=true, $date=null)
 120 {
 121         global $TS;
 122
 123         $dec = user_price_dec();
 124
 125         $itemdata = get_base_taxdata($stock_id, $group_id);
 126         $vat_category = $itemdata['vat_category'];
 127         $item_taxes = $itemdata['taxes'];
 128
 129         $taxopt = $TS->options($trans_type, $itemdata['tax_area'], $vat_category, $allow_reverse);
 130
 131         if (empty($item_taxes))
 132         {
 133                   $ret_array['Net'] = $amount;
 134                   $ret_array['Cost'] = $amount;
 135                   $ret_array['Tax'] = 0;
 136                   if (!is_null($item_taxes))    // register empty taxes only for not fully exempt items
 137                                 $ret_array[] = array('Value'=>0, 'rate' => null, 'tax_type_id' => null, 'Deductible'=>0, 'Adjust' => 0, 'Payable' => 0);
 138         }
 139         else
 140         {
 141                 $ret_array['Net'] = $ret_array['Cost'] = $ret_array['Tax'] = 0;
 142
 143                 $tax_multiplier = 0;
 144
 145                 if ($taxopt&TAX_CHARGED)        // divide tax for net and tax only if charged on document
 146                         foreach ($item_taxes as $taxitem)
 147                                 $tax_multiplier += $taxitem['rate'];
 148
 149                 $partial_vat_percent = get_company_pref('partial_vat_percent');
 150
 151                 foreach ($item_taxes as $tax_id => $item_tax)
 152                 {
 153                                 if ($item_tax['rate'] !== null)
 154                                 {
 155
 156                                         // effective vat for some special purchases is lower than nominal
 157                                         $factor = $vat_category == VC_NONDEDUCT ? 0 : ($vat_category==VC_PARTIAL ? $partial_vat_percent/100.0 : 1);
 158
 159                                         $net_value = $amount;
 160                                         if ($tax_included == true) {
 161                                                 $vat_value = round($amount*$item_tax['rate']/(100+$tax_multiplier), 2);
 162
 163                                                 if ($taxopt&TAX_CHARGED)
 164                                                         $net_value -= $vat_value;
 165
 166                                         } else {
 167
 168                                                 $vat_value = round($amount * $item_tax['rate'] / 100, 2);
 169                                         }
 170
 171                                         $ret_array['Net'] = round2($net_value, $dec);
 172                                 $ret_array['Cost'] = $ret_array['Net'];
 173
 174                                         $tax = array('Value' => 0, 'Deductible' => 0, 'Adjust' => 0, 'Payable' => 0);
 175
 176                                 $tax['purchasing_gl_code'] = $item_tax['purchasing_gl_code'];
 177                                 $tax['sales_gl_code'] = $item_tax['sales_gl_code'];
 178                                 $tax['rate'] = $item_tax['rate'];
 179                                         $tax['tax_type_id'] = $item_tax['tax_type_id'];
 180                                         $tax['tax_type_name'] = $item_tax['tax_type_name'];
 181
 182                                         if ($taxopt & TAX_CHARGED)                                                      // tax is charged on document
 183                                                 $tax['Value'] =  round2($vat_value, $dec);
 184
 185                                         if ($taxopt & TAX_PAYABLE)                                                       // transaction is taxable
 186                                                 $tax['Payable'] =  round2($vat_value, $dec);
 187
 188                                 if ($taxopt & TAX_DEDUCTIBLE) // tax is deductible
 189                                 {
 190                                                 $tax['Deductible'] = round2($vat_value*$factor, 2); // [4815] To avoid rounding issues if $dec > 2 decimal places
 191                                                 $tax['Adjust'] = round2(-(1-$vat_factor)*$factor*$vat_value, $dec); // adjustment due to mixed taxed/exmpt sales activity
 192                                     } else {
 193                                                 $tax['Deductible'] = 0;
 194                                                 $tax['Adjust'] = 0;
 195                                         }
 196                                 $ret_array['Cost'] += $tax['Value'] + ($tax['Payable'] - $tax['Deductible']);// - $tax['Adjust'];
 197
 198                                 $ret_array[] = $tax;
 199                                         $ret_array['Tax'] += $tax['Value'];
 200                                 }
 201                 }
 202         }
 203     $ret_array['vat_category'] = $vat_category;
 204         return $ret_array;
 205 }
 206
 207 //-----------------------------------------------------------------------------------
 208 // return an array of (tax_type_id, tax_type_name, sales_gl_code, purchasing_gl_code, rate, included_in_price, Value, Net)
 209 //
 210 // $vat_factors - effective part of vat values included in tax; calculated but not included vat is added to net value
 211 //
 212 function get_tax_for_items($trans_type, $items, $prices, $shipping_cost, $tax_group, $tax_included=null,
 213         $tax_algorithm = null, $vat_factors = null, $allow_reverse = true)
 214 {
 215
 216         // if shipping cost is passed, just add to the prices/items tables
 217         if ($shipping_cost != 0)
 218         {
 219                 $items[] = null;
 220                 $prices[] = $shipping_cost;
 221                 if ($vat_factors)
 222                         $vat_factors[] = 1;
 223         }
 224
 225         // calculate tax sums
 226         $ret_tax_array = array();
 227         foreach($items as $i => $stock_id)
 228         {
 229                 $taxdata = split_item_price($stock_id, $prices[$i], $tax_group, $tax_included, $trans_type,
 230                          $vat_factors ? $vat_factors[$i] : 1, $allow_reverse, $date=null); // FIXME: $date
 231
 232                 foreach ($taxdata as $key => $data)
 233                 {
 234                         if (is_numeric($key))
 235                         {
 236                                 $tax_id = isset($data['tax_type_id']) ? $data['tax_type_id'] : 'exempt';
 237
 238                                 if (!isset($ret_tax_array[$tax_id]))
 239                                 {
 240                                         $ret_tax_array[$tax_id] = $data;
 241                                         $ret_tax_array[$tax_id]['Net'] = $taxdata['Net'];
 242                                         $ret_tax_array[$tax_id]['vat_category'] = $taxdata['vat_category'];
 243                                 }
 244                                 else
 245                                 {
 246                                         foreach(array('Value', 'Payable', 'Deductible', 'Adjust') as $amt)
 247                                                 $ret_tax_array[$tax_id][$amt] += $data[$amt];
 248                                         $ret_tax_array[$tax_id]['Net'] += $taxdata['Net'];
 249                                 }
 250                         }
 251                 }
 252         }
 253
 254         if (!$tax_algorithm)
 255                 $tax_algorithm = get_company_pref('tax_algorithm');
 256
 257         if ($tax_algorithm == TCA_TOTALS) { // ?
 258                 $dec = user_price_dec();
 259                 // update taxes with
 260                 foreach($ret_tax_array as $index => $item_tax) {
 261                         if ($ret_tax_array[$index]['Value'])
 262                                 $ret_tax_array[$index]['Value'] = round2($item_tax['Net'] * $item_tax['rate'] / 100, $dec);
 263                 }
 264         }
 265
 266         return $ret_tax_array;
 267 }
 268
 269
 270 //---------------------------------------------------------------------------------
 271
 272 // returns the price of a given item minus any included taxes
 273 // for item $stock_id with line price $price and supplier/customer group_id $tax_group
 274
 275 function get_tax_free_price_for_item($trans_type, $stock_id, $price, $tax_group, $tax_included, $allow_reverse = true)
 276 {
 277         // if price is zero, then can't be taxed !
 278         if ($price == 0)
 279                 return 0;
 280
 281         if ($tax_included==0) return $price;
 282
 283         $taxdata = split_item_price($stock_id, $price, $tax_group, $tax_included, $trans_type, 1, $allow_reverse);
 284
 285         return $taxdata['Net'];
 286 }
 287 //
 288 //      Full price (incl. VAT) for item $stock_id
 289 //      calculated for line price $price, and applicable group $tax_group
 290 //
 291 function get_full_price_for_item($trans_type, $stock_id, $price, $tax_group, $tax_included, $allow_reverse = true)
 292 {
 293         // if price is zero, then can't be taxed !
 294         if ($price == 0)
 295                 return 0;
 296
 297         if ($tax_included==1) return $price;
 298
 299         $taxdata = split_item_price($stock_id, $price, $tax_group, $tax_included, $trans_type, 1, $allow_reverse);
 300
 301         return $taxdata['Net'] + $taxdata['Tax'];
 302 }