The invoice is a tax document. Under the Tax code, namely article 169, the document may be issued both on paper and in electronic form. If you use the second option, the copy with all signatures and stamps must be present and in paper form, as when checking tax inspectors require exactly this kind of document.
The invoice is necessary for accounting of business operations related to transactions of purchase and sale, rendering of services. It is in this document indicates the amount of the transaction, the VAT amount also contains information on the name of the subject of the agreement, the meter and the cost per unit of output.
Upon receipt of the invoice, the bookkeeper should reflect the transaction in the account, register the invoice in the purchase Ledger. If the product is sold to another person or the service is provided, then invoiced, the invoice recorded in the sales book.
This tax document must be prepared in accordance with the requirements of Russian legislation (that is, contain information about the vendor and the buyer to have a serial number and the date of preparation, name and quantity of the goods, price and value, the tax rate and the VAT amount. If the invoice is provided when you deal with foreign companies, must indicate the country of manufacturer of the goods and the customs Declaration number.
And it always heads of the enterprises should be invoice? In that case, if the person is exempt from value added tax, it is entitled not to put this tax document. But in that case, if he will put it to the address of buyer, no biggie. Only in the "VAT Rate" should specify: "Without VAT" and not "0%".