Setting up member-tier and birthday offers

First create tiers under Settings → Member Tiers (e.g. Gold), then target the promotion at that tier. For birthday offers, set the audience to Birthday month and fill in Per-customer limit.

• The member must be selected at checkout for the offer to trigger — eligibility is judged against the currently selected member.
• Birthday eligibility reads the member's birthday month, so fill in the birthday field; members without one are never treated as birthday customers.
• A birthday-month promotion needs a per-customer limit, counted per calendar year: a limit of 1 means each customer can use it once a year, and it resets the next year. It can't be saved without one.
• Auto tier upgrades are judged when checkout completes; if the order is voided, an upgrade it triggered is rolled back automatically.