A simple task for a secret operation ;)

task.php

<?php
    
    $date = date('d-m-Y');
    $currentMonth = explode("-", $date)[1];
    $currentYear = explode("-", $date)[2];
    
    $response = array();
    
    for ($i = $currentMonth; $i <= 12; $i++) {
        
        // Getting name of the month from i
        $dateObj   = DateTime::createFromFormat('!m', $i);
        $monthName = $dateObj->format('F');
        
        echo $monthName . "\t";
        
        // Getting the date of the last working day in the month
        
        $lastWorkingdate = getLastWorkingDayByMonth($i, $currentYear);
        echo getLastWorkingDayByMonth($i, $currentYear) . "\t";
        
        $bonusDate = getBonusDayByMonth($i, $currentYear);
        echo $bonusDate . "\n";
        
        $json = new \stdClass(); // Don't know why this is required
        $json->Month = $monthName;
        $json->Salaries_Payment_Day = $lastWorkingdate;
        $json->Bonus_Payment_Day = $bonusDate;
        
        array_push($response, $json);
        
    }

    echo "\n";    
    echo json_encode($response);
    



    // The following function takes the numner (9) and year (2019) as arguments and returns the date of the last working day of the month.
    // Saturday and Sunday are not conidered as the working days
    function getLastWorkingDayByMonth($month, $year) {
        $numberOfDaysInCurrentMonth = cal_days_in_month(CAL_GREGORIAN, $month, $year);
        $unixTimestamp = strtotime($numberOfDaysInCurrentMonth . '-' . $month . '-' . $year);
        
        $dayOfWeek = date("l", $unixTimestamp);
        
        if($dayOfWeek == "Saturday") {
            return $numberOfDaysInCurrentMonth - 1;
        } else if($dayOfWeek == "Sunday") {
            return $numberOfDaysInCurrentMonth - 2;
        } else {
            return $numberOfDaysInCurrentMonth;
        }
    }
    
    function getBonusDayByMonth($month, $year) {
        $numberOfDaysInCurrentMonth = cal_days_in_month(CAL_GREGORIAN, $month, $year);
        $unixTimestamp = strtotime($numberOfDaysInCurrentMonth . '-' . $month . '-' . $year . " +15 days");
        $dayOfWeek = date("l", $unixTimestamp);
        
        if($dayOfWeek == "Saturday" || $dayOfWeek == "Sunday") {
            // Finding first thursday after 15th
            
            for ($i = 1; $i < 7; $i++) {
                 $unixTimestamp = strtotime($numberOfDaysInCurrentMonth . '-' . $month . '-' . $year . " +" . (15 + $i)." days");
                 $dayOfWeek = date("l", $unixTimestamp);
                 if($dayOfWeek == "Thursday") {
                     return $i + 15;
                 }
            }
            
        } else {
            return 15;
        }
        
        echo $dayOfWeek;
    }
?>

/*
September   30  15 
October     31  15 
November    29  19 
December    31  15 

[
    {
        "Month":"September",
        "Salaries_Payment_Day":30,
        "Bonus_Payment_Day":15
    },{
        "Month":"October",
        "Salaries_Payment_Day":31,
        "Bonus_Payment_Day":15
    },{
        "Month":"November",
        "Salaries_Payment_Day":29,
        "Bonus_Payment_Day":19
    },{
        "Month":"December",
        "Salaries_Payment_Day":31,
        "Bonus_Payment_Day":15
    }
]
*/