With grandfathered prices the comparison inverts: a business plan bought when
it cost less than today's team plan would have treated a move to team as an
upgrade — charged immediately, while the customer loses resources. The plan's
rank is frozen with the rest of the snapshot and decides the direction; prices
only decide the amount.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The plan catalogue describes what we sell today; a customer who signed up last
year bought last year's terms. Every commercially relevant condition — price,
quotas, seats, the hardware behind the plan — is now frozen onto a subscription
at signup, and the model refuses to let any of it be rewritten afterwards. A
price rise applies to new subscriptions and cannot reach back into an existing
contract.
PlanChange holds the two rules, computed against the frozen price rather than
today's catalogue:
- Upgrading is immediate and pro rata: the new plan for the days left in the
paid term, minus what the old plan was worth over those same days. On the
last day of a month that is one day's difference, not a month's.
- Downgrading waits for the end of the term. A yearly customer bought a year
and can move down when it is up; a month is a month. A mid-term downgrade is
a goodwill decision, not a self-service button, and its credit covers only
the unused part of the difference.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A timestamp alone said "some number was checked once": editing the field left
it intact, so a customer could swap a verified foreign VAT ID for any
plausible-looking one and keep zero-VAT pricing. The verified value is stored
and compared, which makes the rule self-enforcing — no writer has to remember
to clear a flag, and there are several writers.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Any non-empty string starting with two characters other than AT switched the
customer to reverse charge — typing "XX123" was a 20 % discount. Reverse charge
now requires a VAT ID that is verified, belongs to an EU member state other than
ours, and looks like a VAT number at all. Unverified is the normal state and
means the domestic rate: over-collecting is correctable, under-collecting is a
tax liability.
Changing the number clears its verification. Verification itself (VIES) is not
built yet, so reverse charge stays off until someone confirms a number — which
is the safe direction to be wrong in.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Codex was right that this could misstate real charges: an EU business with a
VAT ID registered in another country is billed under reverse charge, and we
were adding 20 % Austrian VAT to their total anyway. TaxTreatment resolves it
from the customer's VAT ID, and the whole page — cart, plan cards, add-on
cards — now states one treatment instead of contradicting itself.
Explicitly NOT handled: cross-border sales to private individuals, which are
taxed at the buyer's national rate under OSS. That needs a maintained rate
table and a tax adviser, not a guess, so those fall back to the domestic rate —
over-collecting rather than under-collecting.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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