Taxes

[Jon Bosak <bosak@pinax.com>]

Hello PSC,

I need some help figuring out the definitions relating to taxes.  Here's
what appears to be the structure of TaxTotal, leaving out some
unnecessary details (the number 1 indicates exactly one required):

   TaxTotal
      TaxSubtotal (0..n)
         TaxAmount (1)
         ...
         Percent
         ...
         TierRange
         TierRatePercent
         TaxCategory (1)
            ...
            TierRange
            TierRatePercent
            TaxScheme (1)
               ... scheme info ...

1. TierRange and TierRatePercent under TaxSubtotal appear to be
redundant, since these same items will also necessarily appear in
TaxSubtotal under the required TaxCategory.  What am I missing here?

2. There is exactly one TaxCategory and one TaxScheme for each
TaxSubtotal (which has exactly one TaxAmount).  I'm trying to interpret
TaxAmount in TaxSubtotal as the number you get by applying the tax rate
(Percent) to a given amount after categorizing the given amount in its
TaxCategory within the given TaxScheme.  In other words, only one
TaxCategory in each TaxScheme should apply to the given amount.  But I'm
having trouble reconciling this picture with the definition of TaxTotal
as "Information about a total amount of a particular type of tax" when
TaxTotal is (presumably) the total of its 0..n TaxSubtotals, and I'm
also having trouble with the definition of TaxAmount in TaxTotal as "The
total tax amount for particular tax scheme e.g. VAT; the sum of each of
the tax subtotals for each tax category within the tax scheme", which
seems to be saying that TaxSubtotal is the sum of multiple TaxCategories
within one TaxScheme.  I'd appreciate it if someone could describe the
relationship between total, subtotal, category, and scheme more clearly
than I've been able to figure out thus far.

Jon