It may be already mentioned above, but it is a requirement of VAT registered businesses to submit VAT returns to the tax authority of their country, and also to submit annual statistics returns. So the details stored by Ubercart must be able to produce these reports for a given date range.

I'm VAT-registered in Ireland. Here is the information required on my VAT3 return, which is the one I have to send to the Revenue Commissioners (tax authority) every 2 months. I've left off items that aren't relevent to Ubercart (eg items that my company purchased)

• Total VAT on Sales (a total of VAT charged at ALL rates)
• Value of goods sent to EU countries (i.e. sales where VAT not charged because selling into another country to a VAT-registered customer)

Once a year, I also have to fill out a "VAT Return of Trading Details" form. The details which are relevent to Ubercart are a breakdown by each VAT Rate, the total amount of sales at that rate. Note that the VAT rates include several zero rates:

• Exempt - this is treated as different from a 0% rate, even though both charge no VAT. For example, most food is EXEMPT, but Training services are 0%. (There are reasons for this but I won't get into it here. It does point out a requirement for Ubercart to allow for an Exempt and a 0% rate though).
• 0% home - this is items charged at 0% sold within Ireland
• 0% exports - this includes both exports outside the EU, and exports within the EU to VAT-registered companies. In both cases, no VAT would be charged.
• 13.5% - Sales (without VAT) that were charged at 13.5%
• 21% - Sales (without VAT) that were charged at 21%

The rates would differ country to country of course.