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 (purchases, not used for now; depends on whthere it is related to exempt or taxed sales)
  99                 $allow_reverse - option for invoice - whether to honour reverse charging (depends on customer tax status)
 100
 101         Returned array contains calculated values for GL postings and tax registration:
 102                 'Net' - value without tax,
 103                 'Tax' - tax sum,
 104                 'Cost' - cost value (can be higher then Net value),
 105                 'vat_category' -  stock tax category
 106
 107         and (with numeric keys) detailed info for any applicable tax rate:
 108                 'tax_type_id' - tax type id
 109                 'Value' - charged tax value
 110                 'Deductible' - tax deductible (can be lower than Value for special goods or mixed sales structure)
 111                 'Payable' - tax payable
 112                 'Adjust' - additional adjustment to deductible tax due to sales structure factor
 113                 'rate' - tax rate
 114                 'sales_gl_code' - sales tax GL account
 115                 'purchasing_gl_code' - purchase tax GL account
 116                 'tax_type_name' - name of tax type
 117
 118         Price value is splitted as follows:
 119                 Tax: sum of Value (for applicable taxes)
 120                 Net: amount - Tax
 121                 Cost: Net + sum(Payable-Deductible)
 122          for every applicable tax rate:
 123                 Value: tax calculated or 0
 124                 Deductible: vat_factor*Value or 0
 125                 Adjust: Value-Deductible or 0
 126                 Payable: 0 or Value
 127 */
 128 function split_item_price($stock_id, $amount, $group_id, $tax_included=false, $trans_type=ST_SUPPINVOICE, $vat_factor = 1,
 129         $allow_reverse=true)
 130 {
 131         global $TS;
 132
 133         $dec = user_price_dec();
 134
 135         $itemdata = get_base_taxdata($stock_id, $group_id);
 136         $vat_category = $itemdata['vat_category'];
 137         $item_taxes = $itemdata['taxes'];
 138
 139         $taxopt = $TS->options($trans_type, $itemdata['tax_area'], $vat_category, $allow_reverse);
 140
 141         if (empty($item_taxes))
 142         {
 143                   $ret_array['Net'] = $amount;
 144                   $ret_array['Cost'] = $amount;
 145                   $ret_array['Tax'] = 0;
 146                   if (!is_null($item_taxes))    // register empty taxes only for not fully exempt items
 147                                 $ret_array[] = array('Value'=>0, 'rate' => null, 'tax_type_id' => null, 'Deductible'=>0, 'Adjust' => 0, 'Payable' => 0);
 148         }
 149         else
 150         {
 151                 $ret_array['Net'] = $ret_array['Cost'] = $ret_array['Tax'] = 0;
 152
 153                 $tax_multiplier = 0;
 154
 155                 if ($taxopt&TAX_CHARGED)        // divide tax for net and tax only if charged on document
 156                         foreach ($item_taxes as $taxitem)
 157                                 $tax_multiplier += $taxitem['rate'];
 158
 159                 $partial_vat_percent = get_company_pref('partial_vat_percent');
 160
 161                 foreach ($item_taxes as $tax_id => $item_tax)
 162                 {
 163                                 if ($item_tax['rate'] !== null)
 164                                 {
 165
 166                                         // effective vat for some special purchases is lower than nominal
 167                                         $factor = $vat_category == VC_NONDEDUCT ? 0 : ($vat_category==VC_PARTIAL ? $partial_vat_percent/100.0 : 1);
 168
 169                                         $net_value = $amount;
 170                                         if ($tax_included == true) {
 171                                                 $vat_value = round($amount*$item_tax['rate']/(100+$tax_multiplier), 2);
 172
 173                                                 if ($taxopt&TAX_CHARGED)
 174                                                         $net_value -= $vat_value;
 175
 176                                         } else {
 177
 178                                                 $vat_value = round($amount * $item_tax['rate'] / 100, 2);
 179                                         }
 180
 181                                         $ret_array['Net'] = round2($net_value, $dec);
 182                                 $ret_array['Cost'] = $ret_array['Net'];
 183
 184                                         $tax = array('Value' => 0, 'Deductible' => 0, 'Adjust' => 0, 'Payable' => 0);
 185
 186                                 $tax['purchasing_gl_code'] = $item_tax['purchasing_gl_code'];
 187                                 $tax['sales_gl_code'] = $item_tax['sales_gl_code'];
 188                                 $tax['rate'] = $item_tax['rate'];
 189                                         $tax['tax_type_id'] = $item_tax['tax_type_id'];
 190                                         $tax['tax_type_name'] = $item_tax['tax_type_name'];
 191
 192                                         if ($taxopt & TAX_CHARGED)                                                      // tax is charged on document
 193                                                 $tax['Value'] =  round2($vat_value, $dec);
 194
 195                                         if ($taxopt & TAX_PAYABLE)                                                       // transaction is taxable
 196                                                 $tax['Payable'] =  round2($vat_value, $dec);
 197
 198                                 if ($taxopt & TAX_DEDUCTIBLE) // tax is deductible
 199                                 {
 200                                                 $tax['Deductible'] = round2($vat_value*$factor, 2); // avoid rounding issues if $dec > 2 decimal places
 201                                                 $tax['Adjust'] = round2(-(1-$vat_factor)*$factor*$vat_value, $dec); // adjustment due to mixed taxed/exmpt sales activity
 202                                     } else {
 203                                                 $tax['Deductible'] = 0;
 204                                                 $tax['Adjust'] = 0;
 205                                         }
 206
 207                                         if ($tax['Payable'])
 208                                         $ret_array['Cost'] += ($tax['Payable'] - $tax['Deductible']);
 209                                     elseif ($tax['Deductible'])
 210                                         $ret_array['Cost'] += $tax['Adjust'];
 211
 212                                 $ret_array[] = $tax;
 213                                         $ret_array['Tax'] += $tax['Value'];
 214                                 }
 215                 }
 216         }
 217     $ret_array['vat_category'] = $vat_category;
 218         return $ret_array;
 219 }
 220
 221 //-----------------------------------------------------------------------------------
 222 // return an array of (tax_type_id, tax_type_name, sales_gl_code, purchasing_gl_code, rate, included_in_price, Value, Net)
 223 //
 224 // $vat_factors - effective part of vat values included in tax; calculated but not included vat is added to net value
 225 //
 226 function get_tax_for_items($trans_type, $items, $prices, $shipping_cost, $tax_group, $tax_included=null,
 227         $tax_algorithm = null, $vat_factors = null, $allow_reverse = true)
 228 {
 229
 230         // if shipping cost is passed, just add to the prices/items tables
 231         if ($shipping_cost != 0)
 232         {
 233                 $items[] = null;
 234                 $prices[] = $shipping_cost;
 235                 if ($vat_factors)
 236                         $vat_factors[] = 1;
 237         }
 238
 239         // calculate tax sums
 240         $ret_tax_array = array();
 241         foreach($items as $i => $stock_id)
 242         {
 243                 $taxdata = split_item_price($stock_id, $prices[$i], $tax_group, $tax_included, $trans_type,
 244                          $vat_factors ? $vat_factors[$i] : 1, $allow_reverse);
 245
 246                 foreach ($taxdata as $key => $data)
 247                 {
 248                         if (is_numeric($key))
 249                         {
 250                                 $tax_id = isset($data['tax_type_id']) ? $data['tax_type_id'] : 'exempt';
 251
 252                                 if (!isset($ret_tax_array[$tax_id]))
 253                                 {
 254                                         $ret_tax_array[$tax_id] = $data;
 255                                         $ret_tax_array[$tax_id]['Net'] = $taxdata['Net'];
 256                                         $ret_tax_array[$tax_id]['vat_category'] = $taxdata['vat_category'];
 257                                 }
 258                                 else
 259                                 {
 260                                         foreach(array('Value', 'Payable', 'Deductible', 'Adjust') as $amt)
 261                                                 $ret_tax_array[$tax_id][$amt] += $data[$amt];
 262                                         $ret_tax_array[$tax_id]['Net'] += $taxdata['Net'];
 263                                 }
 264                         }
 265                 }
 266         }
 267
 268         if (!$tax_algorithm)
 269                 $tax_algorithm = get_company_pref('tax_algorithm');
 270
 271         if ($tax_algorithm == TCA_TOTALS) { // ?
 272                 $dec = user_price_dec();
 273                 // update taxes with
 274                 foreach($ret_tax_array as $index => $item_tax) {
 275                         if ($ret_tax_array[$index]['Value'])
 276                                 $ret_tax_array[$index]['Value'] = round2($item_tax['Net'] * $item_tax['rate'] / 100, $dec);
 277                 }
 278         }
 279
 280         return $ret_tax_array;
 281 }
 282
 283
 284 //---------------------------------------------------------------------------------
 285
 286 // returns the price of a given item minus any included taxes
 287 // for item $stock_id with line price $price and supplier/customer group_id $tax_group
 288
 289 function get_tax_free_price_for_item($trans_type, $stock_id, $price, $tax_group, $tax_included, $allow_reverse = true)
 290 {
 291         // if price is zero, then can't be taxed !
 292         if ($price == 0)
 293                 return 0;
 294
 295         if ($tax_included==0) return $price;
 296
 297         $taxdata = split_item_price($stock_id, $price, $tax_group, $tax_included, $trans_type, 1, $allow_reverse);
 298
 299         return $taxdata['Net'];
 300 }
 301 //
 302 //      Full price (incl. VAT) for item $stock_id
 303 //      calculated for line price $price, and applicable group $tax_group
 304 //
 305 function get_full_price_for_item($trans_type, $stock_id, $price, $tax_group, $tax_included, $allow_reverse = true)
 306 {
 307         // if price is zero, then can't be taxed !
 308         if ($price == 0)
 309                 return 0;
 310
 311         if ($tax_included==1) return $price;
 312
 313         $taxdata = split_item_price($stock_id, $price, $tax_group, $tax_included, $trans_type, 1, $allow_reverse);
 314
 315         return $taxdata['Net'] + $taxdata['Tax'];
 316 }