Should an Invoice Be Signed?

Many freelancers sign their invoices out of habit — not because they have to, but because it feels safer. A signature looks official. It feels like proof. And when money, clients, and taxes are involved, “official” feels comforting.

In reality, most modern invoices are never signed at all — and that’s perfectly normal. According to tax authorities in the EU, the UK, and the US, what makes an invoice valid is not a signature, but the information and traceability behind it.

Let’s look at what really matters, country by country — with real examples.

Do invoices need to be signed at all?

Short answer: no — not in most cases.

An invoice is not a contract. It’s a financial document that records a transaction that has already been agreed upon. The legal obligation to pay usually comes from a contract, email agreement, or accepted offer — not from the invoice itself.

Example:
You agree by email to design a website for €3,000. You deliver the work. The invoice simply documents that agreement. Even unsigned, it is valid.

How validity is actually determined

Across the EU, UK, and US, an invoice is considered valid if it clearly shows:

• who issued it
• who the client is
• what was sold or delivered
• how much is owed
• when it was issued
• which taxes apply (if any)

If these elements are present and accurate, the invoice does its job — signature or not. For more details on what an invoice must contain to be legal, see our article.

Example:
A PDF invoice generated by software, sent by email, stored in your records, and paid by the client is fully valid — even if no one ever signed it. Shall we try creating an invoice online for free?

EU: are signatures required on invoices?

In the European Union, signatures are not required under VAT rules — for paper or electronic invoices.

EU regulations focus on three things:

• authenticity (who issued it)
• integrity (it wasn’t altered)
• legibility (it can be read later)

These are ensured through invoice numbers, accounting systems, and audit trails — not handwritten signatures.

Example:
A VAT invoice sent via invoicing software with a VAT ID, invoice number, and clear tax breakdown is valid without any signature.

UK: what does HMRC require?

HMRC does not require invoices to be signed. This applies to freelancers, contractors, and small businesses alike.

Most UK businesses issue unsigned PDF invoices or automated invoices, and HMRC accepts them as long as required details are present.

Example:
A UK consultant sends monthly invoices via an online invoicing tool. No signature, no stamp — still fully compliant.

US: are signed invoices expected?

In the United States, invoices also do not need signatures. An invoice is treated as a billing document, not a legal agreement.

Payment obligations come from:

• contracts
• purchase orders
• service agreements

The invoice simply reflects that obligation.

Example:
A US-based freelancer sends an invoice through PayPal or Stripe. The platform logs the transaction. No signature is involved — and none is required.

When a signature might make sense

There are situations where a signature can be useful — but not because the law demands it.

For example:

• when an invoice also acts as proof of service acceptance
• when working with government bodies
• when a client’s internal process requires approval
• in very traditional industries

Example:
A corporate client asks for a signed invoice because their finance department requires it for internal approval. In this case, the signature supports their workflow, not legal validity.

So — should an invoice be signed?

If you’re asking “should invoice be signed?”, the practical answer is: usually no.

If your invoice is clear, complete, and linked to a real transaction, it’s valid in the EU, UK, and US — even without a signature.

And if a client ever asks for one, you can always add it. But you don’t need to start there.