Is it safe to enter my clients' invoice amounts into the VAT calculator?

What happens to the numbers you type

When you type an amount into the VAT calculator, code running inside your page handles it: a division or a multiplication, then rounding, and the result appears straight away. There is no submit button and no user account, and the page itself says under the result: Calculated in your browser. Nothing is sent.

So a client's invoice amount, or your monthly sales total, stays on your device. Nobody on our side sees it, because it never reaches us.

How to check for yourself

You do not have to take our word for it. Try this:

1. Open the calculator page and let it finish loading.
2. Disconnect your device from the internet.
3. Type an amount and a rate, and switch between add and extract.
4. The results keep updating as normal, because the calculation needs no connection.

If you are comfortable with browser developer tools, open the Network tab while you type and you will see no request carrying your figures.

What stays your responsibility

• The device: on a shared computer, close the page when you are done and mind what you copy to the clipboard.
• The rate: the tool neither saves it nor suggests an official one, so enter the right rate every time.
• Your records: nothing is stored, so if you need a figure later, use the copy button and paste it into your invoice or sheet.

And the invoice you send the client?

The calculator only gives you figures. If you build the invoice in the Basic invoice generator, it also runs in your browser, but the file becomes your responsibility once downloaded: where you keep it, who you share it with and how you send it. The template is basic and is not a certified e-invoicing system.

One last point: safety here is about privacy, not about getting the tax right. The calculator gives no tax advice, and the rate that applies to you is for your tax authority or accountant to confirm.