Welcome to a quick tutorial on how to calculate VAT and GST in PHP. Working on your own eCommerce platform in PHP? Trying to figure out how tax should be calculated?
- To calculate the grand total with tax in PHP –
$grand = $total * ((100 + TAX PERCENT) / 100);
- To get the taxable amount –
$tax = $total * (TAX PERCENT / 100);
That should cover the basics, but read on if you need more examples!
TABLE OF CONTENTS
DOWNLOAD & NOTES
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EXAMPLE CODE DOWNLOAD
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PHP TAX CALCULATIONS
All right, let us now get into the examples of how to calculate GST and VAT in PHP.
1) TAX AMOUNT FOR ALL ITEMS
<?php
// (A) DUMMY ITEMS (NAME => PRICE)
$items = [
"Foo Bar" => 12.34,
"Goo Bar" => 8.76,
"Poo Bar" => 34.56
];
// (B) CALCULATE TOTALS + TAX
$taxrate = 9; // TAX PERCENTAGE
$subtotal = 0;
$tax = 0;
foreach ($items as $name=>$price) {
$itemtax = $price * ($taxrate / 100);
$subtotal += $price;
$tax += $itemtax;
echo "$name (Price) - $price<br>";
echo "$name (Taxable) - $itemtax<br>";
}
// (C) GRAND TOTAL
$grand = $subtotal + $tax;
echo "Subtotal - $subtotal<br>";
echo "Add Tax - $tax<br>";
echo "Grand Total - $grand<br>";
Yep, this example is rather intimidating at first, but keep calm and look carefully.
- We are basically looping through the list of items.
- Calculating the taxable amount for each item.
- Then add them together to get the sub-total, total taxable, and grand total.
2) CALCULATE TOTAL TAXABLE
// (B) CALCULATE TOTALS + TAX
$taxrate = 9; // TAX PERCENTAGE
$subtotal = 0;
$tax = 0;
foreach ($items as $name=>$price) {
$subtotal += $price;
}
// (C) GRAND TOTAL
$tax = $subtotal * ($taxrate / 100);
$grand = $subtotal + $tax;
echo "Subtotal - $subtotal<br>";
echo "Add Tax - $tax<br>";
echo "Grand Total - $grand<br>";
If you don’t need to calculate the taxable amount for each item, this is the faster way – Simply add the prices of all the items to get the sub-total, then calculate the tax and grand total.
3) ALTERNATE WAY TO CALCULATE TAX
// (C) GRAND TOTAL
$grand = $subtotal * ((100 + $taxrate) / 100);
$tax = $grand - $subtotal;
echo "Subtotal - $subtotal<br>";
echo "Add Tax - $tax<br>";
echo "Grand Total - $grand<br>";
Lastly, this is another way to calculate the tax – We directly calculate the grand total and work backward to get the taxable amount.
EXTRA) ROUNDING OFF TO N DECIMAL PLACES
$price = 123.456789;
// (A) ROUND OFF TO 2 DECIMAL PLACES
$rounded = round($price, 2); // 123.46
// (B) CEILING - ALWAYS ROUND UP TO NEXT WHOLE NUMBER
$ceiling = ceil($price); // 124
// (C) FLOOR - ALWAYS ROUND DOWN TO LAST WHOLE NUMBER
$ceiling = ceil($price); // 123
Yep, the native PHP rounding functions should be enough in most cases.
EXTRA) ROUND TO NEAREST QUARTER DECIMAL
// (A) THE AMOUNT
$price = 123.47;
// (B) WHOLE & DECIMAL PARTS
$whole = floor($price);
$decimal = $price - $whole;
// (C) ROUND OFF
// 0.01 TO 0.24- ROUND DOWN TO 0.
// 0.25 TO 0.49 – ROUND UP TO 0.5.
// 0.51 TO 0.74 – ROUND DOWN TO 0.5.
// 0.75 TO 0.99 – ROUND UP TO 1.
if ($decimal < 0.25) { $price = $whole; }
else if ($decimal >= 0.25 && $decimal <0.75) { $price = $whole + 0.5; }
else { $price = $whole + 1; }
echo $price;
Take note that some companies or regions may have very specific rounding rules. For example, I once worked with a POS that rounded off to the nearest 5 cents:
- 0.01 to 0.24- Round down to 0.
- 0.25 to 0.49 – Round up to 0.5.
- 0.51 to 0.74 – Round down to 0.5.
- 0.75 to 0.99 – Round up to 1.
So ask your client if you are not sure. Consulting an accountant is the best way to get the rounding right.
EXTRA BITS & LINKS
That’s all for the tutorial, and here is a small section on some extras and links that may be useful to you.
LINKS & REFERENCES
- Calculate GST VAT In Javascript – Code Boxx
THE END
Thank you for reading, and we have come to the end. I hope that it has helped you to better understand, and if you want to share anything with this guide, please feel free to comment below. Good luck and happy coding!