How to Sign an Invoice Online
Sign off on an invoice or statement of work online in minutes. Capture the approver, amount, and date with a tamper-evident audit trail. No account for the approver.
Signing an invoice is not the same as signing a contract. When a client signs an invoice, they are not negotiating terms, they are approving the charges: confirming that the work was delivered, the amount is correct, and the bill is cleared for payment. That sign-off is what unblocks accounts payable, satisfies an internal approval policy, and gives the issuer something concrete to point to if the client later disputes the bill or drags out payment. The same applies to a statement of work or a final timesheet that needs a manager to acknowledge it before it gets billed.
The problem is that most invoice approvals still happen as a forwarded email or a verbal yes, neither of which proves who approved what or when. sign.pink fixes that without the cost and friction of enterprise e-sign tools. For three dollars a month with no envelope caps and no per-seat fees, the issuer uploads the invoice, places an approval signature and a few fields, and sends it to the client. The approver signs in their browser with no account required, and the finished PDF comes back sealed with a tamper-evident audit trail recording who approved it, the amount, and the exact time. Here is how to send an invoice for sign-off and get a record you can stand behind.
Who signs & what it needs
The issuer (the vendor, contractor, or supplier who raised the invoice) sends it, and the client's authorized approver (often an accounts payable contact, project manager, or budget owner) signs to confirm the charges are accepted for payment.
- Invoice number and the issuer's business name
- Total amount due and the currency
- Invoice date and payment due date
- Purchase order or project / statement of work reference (if any)
- Approver's full name and job title
- Approval signature and the date signed
Is it legally binding?
An invoice is not a contract on its own; it is a request for payment, and a signed invoice is best understood as documented acceptance of the charges rather than the agreement that created the obligation. That sign-off still carries real weight. Under the ESIGN Act (2000) and UETA (1999, adopted by 49 states plus DC, with New York applying its own Electronic Signatures and Records Act), an electronic approval is given the same legal effect as an ink signature when the approver intends to sign and agrees to do business electronically, and in the EU electronic signatures are recognized under eIDAS (Regulation (EU) No 910/2014). The practical value of signing an invoice is evidentiary: if a client later claims the work was never accepted or the amount was wrong, a signed approval tied to a tamper-evident audit trail showing who signed, the amount they approved, and when is exactly the kind of record that supports your position, consistent with how the US Federal Rules of Evidence 901 and 902 address authentication of records. Keep in mind that the signature confirms acceptance of the bill, not the underlying tax or accounting treatment, and this is general information rather than legal advice.
How to sign a invoice on sign.pink
- 1
Finalize the invoice and save it as a PDF
Generate the invoice in your billing or accounting software and export it as a PDF so the line items, total, and dates are locked in place. If it covers a statement of work or timesheet, attach or merge that into the same PDF so the approver signs off on the work and the amount together.
- 2
Upload the invoice to sign.pink
Open sign.pink in any browser on your phone or computer and upload the PDF. There is nothing to install. The invoice loads exactly as the client will see it, so the figure they approve matches the figure you billed.
- 3
Add the client's approver
Enter the name and email of the person authorized to approve the charge, such as the accounts payable contact, project manager, or budget owner. They do not need a sign.pink account, so any work email will do. Add more than one approver if your client requires a second sign-off.
- 4
Place the approval fields
Drop a signature field where the approval belongs, plus an approval date field and a text field for the approver's name and title. Add a checkbox or note field if you want them to confirm the work was received as described. Mark the signature and date as required so nothing comes back blank.
- 5
Send it for sign-off and track status
Send the invoice. The approver gets a secure link, opens the PDF in their browser, reviews the amount, and signs in seconds with no account or app. From your documents view you can see whether it is still pending or approved, and follow up at no extra cost since there are no envelope caps.
- 6
Download the signed invoice and audit trail
Once the approver signs, sign.pink seals the invoice and attaches a tamper-evident audit trail recording who approved it, the email they signed from, a timestamp, and a SHA-256 hash that detects any later change. File the signed PDF with your accounts receivable records as proof the charge was accepted for payment.
Signing a invoice — FAQ
An emailed invoice proves you sent a bill, but it does not prove the client accepted the charges. A signed approval does. It captures that a named, authorized person agreed the work was delivered and the amount is correct, which is what clears the invoice through accounts payable and gives you firm evidence if payment is later questioned or disputed. On sign.pink that approval comes with a tamper-evident audit trail, so the acceptance is documented, not just claimed.
Sign your invoice in minutes.
No credit card to start. No envelope limits. No surprises.