The invoice: what it is and what it does not prove
The seller or contractor issues an invoice so the buyer knows how much to pay and where. It lists the parties, a number and date, the items with quantities and prices, the currency, the total, the tax treatment and bank details. The buyer usually does not need to sign an invoice: it is a one-sided document.
It is important to understand its limits. An invoice does not confirm that goods were handed over, work was performed or a service was provided, and it does not always prove that the parties agreed on the price. Paying an invoice can become evidence of agreeing to its terms, but other documents are needed to show performance.
In some countries, including Russia, there is also a tax document with a similar name, the VAT invoice. These are different documents with different purposes: a tax invoice serves tax accounting and has mandatory details. Do not confuse them when the other side's accountant asks you to send an invoice.
The acceptance certificate: what it records
A certificate of completed work or services is signed by both parties. It answers what exactly was done, for which period, under which contract and for what amount, and whether the client has any objections. Once it is signed, it is harder for the client to claim the work was not done, and the contractor has a document to rely on when asking for payment.
If the client has concerns about quality or scope, it is better to write them directly in the certificate or in a separate reasoned refusal. A signature without reservations usually means agreement with the result. Many contracts describe what happens if the client stays silent, for example that the certificate is deemed signed once the period for objections expires. Find such a clause in the contract in advance.
How the documents work together
A typical sequence looks like this: the contract sets the price and payment terms, the contractor does the work, the parties sign the certificate, and then an invoice is issued or a previously issued one is paid. With prepayment the order is reversed: invoice and payment first, then work and certificate. In both cases it is the contract that defines which of these triggers payment.
For goods, a delivery note or another transfer document is used instead of a certificate. Some accounting systems use universal forms that combine several functions. It is better to ask your counterparty in advance which document they need rather than after delivery.
Checklist: what to check
For the invoice: correct names and details of the parties; number and date; a reference to the contract, if there is one; clear items with quantities and prices; currency; tax treatment, meaning tax on top of the price, included in it or not charged; a total that matches the items; a payment due date.
For the certificate: a reference to the contract and the period; a list of work that matches the subject of the contract; an amount that matches the contract and the invoice; space for objections or a note that there are none; signatures of authorised people on both sides; the signing date. If anything does not match, correct the document before signing, not after.
Common mistakes
The invoice amount differs from the certificate or the contract. The certificate is dated before the work was actually finished. It lists work that is not in the contract. Someone without authority signs it. Objections were raised orally and never recorded. Another source of confusion is the reconciliation statement: it shows the balance of mutual payments for a period and does not confirm that work was done.
How to do this in Legal
In JEEKSSHIRE 24 | Legal the acceptance certificate and the invoice are separate document types in the creation section. For a certificate the assistant asks for the underlying contract, period, list of work, acceptance and amounts. For an invoice it asks for the invoice type, seller and buyer, items, quantities, prices, currency, tax treatment and rate, including a zero rate. The invoice table with net amounts, tax and total is calculated by the program strictly from your figures: if you have not stated the currency or tax treatment explicitly, Legal asks you to clarify instead of filling them in itself. Party details come from saved profiles, the document is saved as PDF or DOCX, and you can place a drawn signature on the finished PDF. Creating documents is available with a paid subscription; checking tax details remains up to you or your accountant.