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         $item_tax_type = get_item_tax_type_for_item($stock_id); // get item tax data
  37         $taxdata['vat_category'] = $item_tax_type['vat_category'];
  38
  39         // if the item is exempt from all taxes thats all
  40         if ($item_tax_type["exempt"])
  41                 return $taxdata;
  42
  43         $taxdata['taxes'] = array();
  44
  45         // get the exemptions for this item tax type
  46         $item_tax_type_exemptions_db = get_item_tax_type_exemptions($item_tax_type["id"]);
  47
  48         // read them all into an array to minimize db querying
  49         $item_tax_type_exemptions = array();
  50         while ($item_tax_type_exemp = db_fetch($item_tax_type_exemptions_db))
  51         {
  52                 $item_tax_type_exemptions[] = $item_tax_type_exemp["tax_type_id"];
  53         }
  54
  55         $tax_group_items_array = $group_data['taxes'];
  56         // if any of the taxes of the tax group are in the exemptions, then skip
  57         foreach ($tax_group_items_array as $tax_group_item)
  58         {
  59
  60                 $skip = false;
  61
  62                 // if it's in the exemptions, skip
  63                 if (is_null($tax_group_item['rate']))
  64                         $skip = true;
  65                 else
  66                         foreach ($item_tax_type_exemptions as $exemption)
  67                         {
  68                                 if (($tax_group_item['tax_type_id'] == $exemption))
  69                                 {
  70                                 $skip = true;
  71                                 break;
  72                                 }
  73                         }
  74
  75                 if (!$skip)
  76                 {
  77                         $index = $tax_group_item['tax_type_id'];
  78                         $taxdata['taxes'][$index] = $tax_group_item;
  79                 }
  80         }
  81
  82         return $taxdata;
  83 }
  84
  85 /*
  86         Main tax procedure splitting transaction item value according to item tax rules applicable:
  87                 $amount - price/value to be splitted
  88                 $tax_group - entity tax group
  89                 $tax_included - whether value includes all taxes
  90                 $vat_factor - 0-1; tax deduction factor (purchases, not used for now; depends on whthere it is related to exempt or taxed sales)
  91                 $allow_reverse - option for invoice - whether to honour reverse charging (depends on customer tax status)
  92
  93         Returned array contains calculated values for GL postings and tax registration:
  94                 'Net' - value without tax,
  95                 'Tax' - tax sum,
  96                 'Cost' - cost value (can be higher then Net value),
  97                 'vat_category' -  stock tax category
  98
  99         and (with numeric keys) detailed info for any applicable tax rate:
 100                 'tax_type_id' - tax type id
 101                 'Value' - charged tax value
 102                 'Deductible' - tax deductible (can be lower than Value for special goods or mixed sales structure)
 103                 'Payable' - tax payable
 104                 'Adjust' - additional adjustment to deductible tax due to sales structure factor
 105                 'rate' - tax rate
 106                 'sales_gl_code' - sales tax GL account
 107                 'purchasing_gl_code' - purchase tax GL account
 108                 'tax_type_name' - name of tax type
 109
 110         Price value is splitted as follows:
 111                 Tax: sum of Value (for applicable taxes)
 112                 Net: amount - Tax
 113                 Cost: Net + sum(Payable-Deductible)
 114          for every applicable tax rate:
 115                 Value: tax calculated or 0
 116                 Deductible: vat_factor*Value or 0
 117                 Adjust: Value-Deductible or 0
 118                 Payable: 0 or Value
 119 */
 120 function split_item_price($stock_id, $amount, $group_id, $tax_included=false, $trans_type=ST_SUPPINVOICE, $vat_factor = 1,
 121         $allow_reverse=true)
 122 {
 123         global $TS;
 124
 125         $dec = user_price_dec();
 126
 127         $itemdata = get_base_taxdata($stock_id, $group_id);
 128         $vat_category = $itemdata['vat_category'];
 129         $item_taxes = $itemdata['taxes'];
 130
 131         $taxopt = $TS->options($trans_type, $itemdata['tax_area'], $vat_category, $allow_reverse);
 132
 133         if (empty($item_taxes))
 134         {
 135                   $ret_array['Net'] = $amount;
 136                   $ret_array['Cost'] = $amount;
 137                   $ret_array['Tax'] = 0;
 138                   if (!is_null($item_taxes))    // register empty taxes only for not fully exempt items
 139                                 $ret_array[] = array('Value'=>0, 'rate' => null, 'tax_type_id' => null, 'Deductible'=>0, 'Adjust' => 0, 'Payable' => 0);
 140         }
 141         else
 142         {
 143                 $ret_array['Net'] = $ret_array['Cost'] = $ret_array['Tax'] = 0;
 144
 145                 $tax_multiplier = 0;
 146
 147                 if ($taxopt&TAX_CHARGED)        // divide tax for net and tax only if charged on document
 148                         foreach ($item_taxes as $taxitem)
 149                                 $tax_multiplier += $taxitem['rate'];
 150
 151                 $partial_vat_percent = get_company_pref('partial_vat_percent');
 152
 153                 foreach ($item_taxes as $tax_id => $item_tax)
 154                 {
 155                                 if ($item_tax['rate'] !== null)
 156                                 {
 157
 158                                         // effective vat for some special purchases is lower than nominal
 159                                         $factor = $vat_category == VC_NONDEDUCT ? 0 : ($vat_category==VC_PARTIAL ? $partial_vat_percent/100.0 : 1);
 160
 161                                         $net_value = $amount;
 162                                         if ($tax_included == true) {
 163                                                 $vat_value = round($amount*$item_tax['rate']/(100+$tax_multiplier), 2);
 164
 165                                                 if ($taxopt&TAX_CHARGED)
 166                                                         $net_value -= $vat_value;
 167
 168                                         } else {
 169
 170                                                 $vat_value = round($amount * $item_tax['rate'] / 100, 2);
 171                                         }
 172
 173                                         $ret_array['Net'] = round2($net_value, $dec);
 174                                 $ret_array['Cost'] = $ret_array['Net'];
 175
 176                                         $tax = array('Value' => 0, 'Deductible' => 0, 'Adjust' => 0, 'Payable' => 0);
 177
 178                                 $tax['purchasing_gl_code'] = $item_tax['purchasing_gl_code'];
 179                                 $tax['sales_gl_code'] = $item_tax['sales_gl_code'];
 180                                 $tax['rate'] = $item_tax['rate'];
 181                                         $tax['tax_type_id'] = $item_tax['tax_type_id'];
 182                                         $tax['tax_type_name'] = $item_tax['tax_type_name'];
 183
 184                                         if ($taxopt & TAX_CHARGED)                                                      // tax is charged on document
 185                                                 $tax['Value'] =  round2($vat_value, $dec);
 186
 187                                         if ($taxopt & TAX_PAYABLE)                                                       // transaction is taxable
 188                                                 $tax['Payable'] =  round2($vat_value, $dec);
 189
 190                                 if ($taxopt & TAX_DEDUCTIBLE) // tax is deductible
 191                                 {
 192                                                 $tax['Deductible'] = round2($vat_value*$factor, 2); // avoid rounding issues if $dec > 2 decimal places
 193                                                 $tax['Adjust'] = round2(-(1-$vat_factor)*$factor*$vat_value, $dec); // adjustment due to mixed taxed/exmpt sales activity
 194                                     } else {
 195                                                 $tax['Deductible'] = 0;
 196                                                 $tax['Adjust'] = 0;
 197                                         }
 198
 199                                         if ($tax['Payable'])
 200                                         $ret_array['Cost'] += ($tax['Payable'] - $tax['Deductible']);
 201                                     elseif ($tax['Deductible'])
 202                                         $ret_array['Cost'] += $tax['Adjust'];
 203
 204                                 $ret_array[] = $tax;
 205                                         $ret_array['Tax'] += $tax['Value'];
 206                                 }
 207                 }
 208         }
 209     $ret_array['vat_category'] = $vat_category;
 210         return $ret_array;
 211 }
 212
 213 //-----------------------------------------------------------------------------------
 214 // return an array of (tax_type_id, tax_type_name, sales_gl_code, purchasing_gl_code, rate, included_in_price, Value, Net)
 215 //
 216 // $vat_factors - effective part of vat values included in tax; calculated but not included vat is added to net value
 217 //
 218 function get_tax_for_items($trans_type, $items, $prices, $tax_group, $tax_included=null,
 219         $tax_algorithm = null, $vat_factors = null, $allow_reverse = true)
 220 {
 221
 222         // calculate tax sums
 223         $ret_tax_array = array();
 224         foreach($items as $i => $stock_id)
 225         {
 226                 $taxdata = split_item_price($stock_id, $prices[$i], $tax_group, $tax_included, $trans_type,
 227                          $vat_factors ? $vat_factors[$i] : 1, $allow_reverse);
 228
 229                 foreach ($taxdata as $key => $data)
 230                 {
 231                         if (is_numeric($key))
 232                         {
 233                                 $tax_id = isset($data['tax_type_id']) ? $data['tax_type_id'] : 'exempt';
 234
 235                                 if (!isset($ret_tax_array[$tax_id]))
 236                                 {
 237                                         $ret_tax_array[$tax_id] = $data;
 238                                         $ret_tax_array[$tax_id]['Net'] = $taxdata['Net'];
 239                                         $ret_tax_array[$tax_id]['vat_category'] = $taxdata['vat_category'];
 240                                 }
 241                                 else
 242                                 {
 243                                         foreach(array('Value', 'Payable', 'Deductible', 'Adjust') as $amt)
 244                                                 $ret_tax_array[$tax_id][$amt] += $data[$amt];
 245                                         $ret_tax_array[$tax_id]['Net'] += $taxdata['Net'];
 246                                 }
 247                         }
 248                 }
 249         }
 250
 251         if (!$tax_algorithm)
 252                 $tax_algorithm = get_company_pref('tax_algorithm');
 253
 254         if ($tax_algorithm == TCA_TOTALS) { // ?
 255                 $dec = user_price_dec();
 256                 // update taxes with
 257                 foreach($ret_tax_array as $index => $item_tax) {
 258                         if ($ret_tax_array[$index]['Value'])
 259                                 $ret_tax_array[$index]['Value'] = round2($item_tax['Net'] * $item_tax['rate'] / 100, $dec);
 260                 }
 261         }
 262
 263         return $ret_tax_array;
 264 }
 265
 266
 267 //---------------------------------------------------------------------------------
 268
 269 // returns the price of a given item minus any included taxes
 270 // for item $stock_id with line price $price and supplier/customer group_id $tax_group
 271
 272 function get_tax_free_price_for_item($trans_type, $stock_id, $price, $tax_group, $tax_included, $allow_reverse = true)
 273 {
 274         // if price is zero, then can't be taxed !
 275         if ($price == 0)
 276                 return 0;
 277
 278         if ($tax_included==0) return $price;
 279
 280         $taxdata = split_item_price($stock_id, $price, $tax_group, $tax_included, $trans_type, 1, $allow_reverse);
 281
 282         return $taxdata['Net'];
 283 }
 284 //
 285 //      Full price (incl. VAT) for item $stock_id
 286 //      calculated for line price $price, and applicable group $tax_group
 287 //
 288 function get_full_price_for_item($trans_type, $stock_id, $price, $tax_group, $tax_included, $allow_reverse = true)
 289 {
 290         // if price is zero, then can't be taxed !
 291         if ($price == 0)
 292                 return 0;
 293
 294         if ($tax_included==1) return $price;
 295
 296         $taxdata = split_item_price($stock_id, $price, $tax_group, $tax_included, $trans_type, 1, $allow_reverse);
 297
 298         return $taxdata['Net'] + $taxdata['Tax'];
 299 }