MOD required for VAT group discount 1.3.4

Hi All,
I've spent a week on here trying to solve this problem but admit defeat & am willing to pay someone to solve the following:

During the new member registration, customer can declare [tick box] they are eligible for VAT Exemption due to medical illness by completing hidden part of declaration form. They are then registered to a VAT Exempt group which is afforded a 17.5% discount on selected items. Within the site, these items are declared within Product Description page as VAT Exempt.

I have seen this achieved on eghambob's Practical Mobility site & have contacted to see how it was done but apparently was a combination of several contributors. I am happy to pay if someone could manage to get their head around this problem & would be willing to re-post on here for all else to share as know this is a common problem for UK retail clients in a certain type of store. Here's the link to the example site:

http://www.practicalmobility.co.uk

Thanks.

ps - I know Q has a commercial MOD which does this for all products but require this to work only for specific products as VAT discounts in UK can only be offered for Medical necessity items.

Did you get anywhere with this, I have the same issue - I want to apply a 20% VAT discount to certain items if a customer says he is "disabled" - I can't get my head around it at the minute - I'm thinking a product should have one of 3 VAT rates (group 1:zero rate, group 2:20% VAT or group 3:exempt for disabled people) - then ask them if they are exempt when they register for an account if they are, apply a 20% discount to the relevant products in the cart

Is this how you did it? or is there a mod I have missed somewhere?

I would appreciate any advice you could offer me.

I should say I'm using 1.4.9.1

I did after reading this thread: http://forum.opencart.com/viewtopic.php?f=20&t=14477
& thanks to a lot of help from fellow member eghambob - you may want to get in touch with him directly though as was his solution. NB - was for 1.4.7 though.

Dear guys, I just released two contributions to properly manage taxes (one specific for US taxation system, another more general for EU VAT), introducing the new concept of customer tax groups (separate and different from standard customer groups) in registration forms.
For each customer tax group, specific IDs are requested and, when is applicable, tax exemption is applied.
At the moment, tax exemption is global on all products, but I could adapt and improve things in order to apply it only on specific tax classes for specific customer tax groups.

Please have a look at:
http://www.opencart.com/index.php?route ... on_id=2107
or
http://www.opencart.com/index.php?route ... on_id=2004
for more details.

You will find also live demo sites where you can check everything. I'm also available to collect further requirements for next versions.

Please let me know for any comment or clarification,

regards

M