Reduce total VAT when specific product added

[Takoda]

For all products, either normal VAT applies, or zero VAT if the customer is VAT registered; I think we can use the European VAT mod for this.

In orders where installation of the products is also requested, we can edit the shopping cart (login as the customer, or by accessing the db directly) and add the cost of installation.

So far so good...

BUT, for those orders which include installation, we need to charge the normal zero rate for VAT registered customers, or a reduced 5% for those that aren't.

Has anyone any idea how to achieve this, before it gets to the checkout?

[Takoda]

Resolved, using the mod here, modified to allow a customer specific tax/VAT rate to be entered.

This solution only works if all products are taxed the same, and where the customer requests the tax/VAT change, eg on submission of a company tax/VAT number, or other reason - in this case reduction of VAT due to installation being included - before their order is submitted.

Thanks for all your replies.