vatcalculator.php

См. документацию.

<?php
 
namespace Bitrix\Sale\Tax;
 
use Bitrix\Sale\PriceMaths;

class VatCalculator
{
    private float $rate;

    public function __construct(float $rate)
    {
        $this->rate = $rate;
    }

    public function calc(float $price, bool $isVatInPrice, bool $withRound = true): float
    {
        if ($this->rate === 0.0)
        {
            return 0.0;
        }
        elseif ($isVatInPrice)
        {
            $vat = $price * $this->rate / ($this->rate + 1);
        }
        else
        {
            $vat = $price * $this->rate;
        }
 
        return $withRound ? PriceMaths::roundPrecision($vat) : $vat;
    }

    public function allocate(float $price, bool $withRound = true): float
    {
        if ($this->rate === 0.0)
        {
            return $price;
        }
 
        $rate = $this->rate * 100;
        $vat = $price * $rate / ($rate + 100);
        $priceWithoutVat = $price - $vat;
 
        return $withRound ? PriceMaths::roundPrecision($priceWithoutVat) : $priceWithoutVat;
    }

    public function accrue(float $price, bool $withRound = true): float
    {
        $priceWithVat = $price * (1 + $this->rate);
 
        return $withRound ? PriceMaths::roundPrecision($priceWithVat) : $priceWithVat;
    }
}