excel or php formula add fees when invoice delay every 5 month

one text

Solution:

For PHP:

//difference in dates
    $interval = $date1->diff($date2);
    if($interval > 5)
    {
      if($interval>0 && $interval<3)
       {
         $amountNew = (($oldAmount * 0.15)+$oldAmount) + ($oldAmount *0 * 0.005);
       }elseif($interval>3 && $interval<6) //repeat these steps for all the intervals
        {
          $amountNew = (($oldAmount * 0.15)+$oldAmount) + ($oldAmount *3 * 0.005);
        }
          
    }

The above should do the trick for getting the date difference and adding the 15% to the amount. If you are storing the values in a DB, loop through it with a for loop or foreach.

for Excel: use the following formula: Datedif(cellofdate1; cellofdate2; "m") this will give you the difference in months the you can wrap it in an if

IF(DATEDIF(DATE1;DATE2;"M")>5;IF(DATEDIF(DATE1;DATE2;"M")=3;((AMOUNT*0,15)+AMOUNT) + (AMOUNT*3*0,005);E1)

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