The calculation of VAT in Italy is a fairly simple task, since the flat tax at 22%, hoping to keep it that.
Suppose we decide to buy an asset, the cost of which is 130 EUR, excluding VAT. How do you calculate the final price including VAT at 22%? Just take the amount shown in the budget, multiply it by 22 and then divide by 100. The result then is added to the net cost.
The formula then apply is very simple:
130 x 22 100 = 28.6 € (VAT 22%)
130 + 28.6 = 158.6 Euros (total price including VAT).
Basically we're going to calculate the tax of 22% on taxable (the cost of the product or service on which to add the VAT) and add it asessment same, thus obtaining the full cost, including VAT.
Since this is a very simple calculation you can do "on the fly" whenever you need them, but we imagine an e-commerce in which the calculation is carried out in many places in the application: back to more comfortable certainly write a function specifically that we can draw on the fly whenever you like.
This tools handles input errors in the boxes and calculates billing adding VAT asessment.
The script can be downloaded for free and can be used for any non-commercial purpose.
You can find this project on my personal website. http://igorredaelli.com/calcolo-iva/