Formulas used:

total = (inter price + expenses + manual_expense ) – early bird + city fee+ cleaning fee + sec deposit

$early_bird_discount – doesn’t include extra guest, security, city fee, cleaning fee

$you_earn = $total_price – $security_deposit – floatval($city_fee) – floatval($cleaning_fee) – $service_fee;

$taxes = round ( $you_earn * $taxes_value/100,2);

$price_for_service_fee = $total_price – $security_deposit – floatval($city_fee) – floatval($cleaning_fee);

city fee % Doesn’t consider price for extra guest

city fee % Doesn’t consider extra expenses (added when owner issues invoice)

100% deposit includes automatically expenses (city fee / cleaning fee) – even if the option is set to NO

How to add a new item in booking formulas

There are many places where you need to do the changes and for that reason it’s difficult to give step by step instructions.
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Start on wprentals-core plugin – file post-types/invoices.php – you have there function wpestate_super_invoice_details and wpestate_invoice_details functions that are used to create and display invoices.
Also a very important function is wpestate_booking_price in wprentals theme folder – file libs/help_functions.php
In this function we do all the math. So you can start by looking into this.