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# Check that a document is the one a business sent

Last checked 2026-11-12

When a business issues a quote, order, invoice or any other document on to.co, to.co signs it with that business's own key. Anyone can check it. You need no account.

## Open the check page

- On a document emailed to you, choose **Check that this is the document {business} sent**.
- On its PDF, under **Check this document**, scan the code or open the link beside it.

Both open the document's check page on the business's own to.co address, such as `https://mybusiness.uk.to.co/verify/…`.

## What the page says

When the document checks out, the page says **Signed for {business}, unchanged since {date}**. It names the kind of document, its number and its issue date. Then it lists:

- the key it was signed with, and where that key is published on the business's to.co address;
- whether the business's own domain publishes the same key in its DNS.

The DNS line is a separate check. If the business has not added its key to a domain of its own, or the DNS could not be read, the page says so. The signature can still check out.

When it does not check out, the page says **This document does not check out**. Do not rely on it. Contact the business through its to.co page.

## Check a PDF you received

Under **Check a file you received**, choose the PDF or drop it on the page. The page says whether it is the signed PDF of that document. The check runs on your device. The file is not uploaded.

When the document went between two businesses on to.co, each side has its own signed PDF. Either one checks out.

## What a check shows, and what it does not

It shows that to.co sent the document for that business, and that it has not changed since. It does not show:

- that a person at the business signed it;
- that the bank details on it are right. Before you pay, compare them with the business's to.co page.

PDF readers such as Adobe Acrobat do not show this signature. It is checked on the page, against the published key.

## For the business that sends

Every document you issue on to.co is signed when you issue it, on every plan, at no cost. That includes a Xero quote or invoice you send with **Send**. It is signed with your business's own key: the same key as in your ABIZ record. To have your own domain confirm it, add your ABIZ record to your domain's DNS. The **ABIZ record** tab in my.to.co shows how.