How to allow the user to choose between entering a price including VAT or exclusive VAT in TextField?

Question

I use a back-office application in which the user enters product prices. Sometimes it is preferable to introduce value added tax, including VAT, and sometimes excluding VAT.

What is the best way to allow the user to choose between included or exclusive VAT in terms of usability ?

I could have two TextFields above eachother, including VAT and one exclusive, and reflect the input. But I don’t think that real-time reflection of input in another TextField is good, when it comes to usability, it distracts the user.

I could also have two Radiobuttons above or below a TextField, or perhaps other than TextField, which allow the user to make a choice.

Or do I have one button to switch between included / exclusive VAT? like on / off buttons. But what text should I have on the button and how should the button be created? I think this is good because it takes up less space and it is easy to have it close to TextField, but it is very difficult to create a good button in usability.

Please give me some recommendations. Some of you may be working with usability or have seen a similar problem.

Answer 1

This question is duplicated on UXExchange , which is probably a more appropriate forum. My answer is, along with potentially many other answers from UX experts.

http://uxexchange.com/questions/2181/how-to-let-the-user-choose-between-typing-price-inclusive-vat-or-exclusive-vat-in

Answer 2

I would suggest using a single text box with the “including VAT” checkbox next to it. Next to this, I would show the price as a plain text (reflecting changes in real time) with or without VAT. Thus, there is only one input area, and the results are visible and obvious.

Answer 3

Your first idea is the best. No, not the one you rejected, with two editable text fields and no buttons, where a record in one text field automatically updates something in another. Any distraction caused by updates is negligible compared to the difficulties of alternatives in which the user has to figure out and activate the button. If you are still worried that the update is distracting, the update occurs when the focus leaves the text field or the Enter key is pressed.