Remove default tax zone validation

[mamhoff]

With the new VAT taxation system, a default zone is no longer mandatory. It is perfectly valid to have
taxes that are included in price only for specific foreign zones.

[cbrunsdon]

👍 from me. Killing this didn't make any tests fail and I don't understand its purpose to begin with.

If someone that actually understands this stuff says kill it, I'm good killing it.

[mamhoff]

Let's wait with this one until we can actually manipulate prices.

Let me quickly explain what's going on here: The default_tax_zone indicates what zone's VATs apply to the prices entered for variants in the backend. So a German user would enter 19.99 for an item whose net price is actually 16.80 (at 19% VAT). As things are now, when you ship to a place outside the default VAT zone, the default zone's VAT would be "refunded".

If you ship to another place with VAT, the German VAT will not be refunded, and the other place's VAT would be applied. This leads to wrong net prices (same prices, different included tax --> crazyness).

Once we have tax-adjusted line item prices, there would be no need for the refunding anymore, as for that case the price for the line item would drop to the net price. It will even be possible for a Solidus integrator to not specify a default zone, and prices would be adjusted up once users decide to ship to Germany.

Really though, I'd say put this on hold and leave it for the time being. We're right now working on improving the taxation tests, and once those tests are in, it'll hopefully be possible to see more clearly what setting a default VAT zone does.

[mtomov]

funny how a custom validation is removed and all tests still pass.

[cbrunsdon]

@mamhoff Are we good to pull the trigger on this one for 1.3? I'm still honestly pretty fuzzy on how it fits into the larger changes.

[mamhoff]

No, we're not. First, I need to be able to recalculate line item prices,
which is like three commits away on the PORO PR.
On Jan 25, 2016 5:07 PM, "Clarke Brunsdon" notifications@github.com wrote:

@mamhoff https://github.com/mamhoff Are we good to pull the trigger on
this one for 1.3? I'm still honestly pretty fuzzy on how it fits into the
larger changes.

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#527 (comment).

[mamhoff]

I cherry-picked that upon #747, because this can only go when that's implemented. Closing.