diff --git a/src/modules/events/components/CreateEventDialog.vue b/src/modules/events/components/CreateEventDialog.vue
index ad8d9c5..b9ad6c1 100644
--- a/src/modules/events/components/CreateEventDialog.vue
+++ b/src/modules/events/components/CreateEventDialog.vue
@@ -342,8 +342,12 @@ const waveErrors = computed(() =>
   validateWaveRows(extraWaves.value, new Set(knownWaveIds.value)),
 );
 const hasWaveErrors = computed(() => Object.keys(waveErrors.value).length > 0);
-/** New waves inherit the primary wave's currency. */
+/** New waves inherit the primary wave's currency and fiat settings. */
 const primaryCurrency = computed(() => form.values.currency ?? "sat");
+const primaryAllowsFiat = computed(
+  () => form.values.payment_methods?.includes("fiat") ?? false,
+);
+const primaryFiatCurrency = computed(() => form.values.fiat_currency ?? "USD");
 
 async function populateFromEvent(event: TicketedEvent) {
   isPopulating.value = true;
@@ -594,7 +598,28 @@ const onSubmit = form.handleSubmit(
         notification_subject: formValues.notification_subject,
         notification_body: formValues.notification_body,
         promo_codes: toWirePromoCodes(promoRows.value),
-        ticket_waves: [primaryWave, ...extraWaves.value],
+        // Fiat is a per-wave opt-in in the extension, but the webapp
+        // offers ONE event-level control for it (the Card checkbox), so
+        // that checkbox governs every wave: ticking Card enables fiat on
+        // all of them, unticking disables it on all of them. Without this a
+        // wave added here refuses card payments while the event itself
+        // reads as fiat-enabled — what organisers hit on demo.
+        //
+        // Deliberately simple for now: it does mean a per-wave setting made
+        // in the LNbits admin is overwritten next time the event is saved
+        // from here. Acceptable while the webapp has no per-wave control to
+        // represent one, and better than a control that silently disagrees
+        // with what gets stored.
+        ticket_waves: [primaryWave, ...extraWaves.value].map((wave) => ({
+          ...wave,
+          allow_fiat: acceptsFiat,
+          // The event's fiat currency, unconditionally — not a fallback to
+          // whatever the wave happened to hold. Waves created before this
+          // carry the backend's "GBP" default, and a wave settling in a
+          // different currency than the event advertises is not a state the
+          // webapp can represent or an organiser can have asked for.
+          fiat_currency: formValues.fiat_currency,
+        })),
       };
 
       if (isEditMode.value) {
@@ -1215,6 +1240,8 @@ const handleOpenChange = (open: boolean) => {
                 v-model="extraWaves"
                 :known-ids="knownWaveIds"
                 :currency="primaryCurrency"
+                :allow-fiat="primaryAllowsFiat"
+                :fiat-currency="primaryFiatCurrency"
                 :disabled="isLoading"
               />
             </CollapsibleContent>
diff --git a/src/modules/events/components/PurchaseTicketDialog.vue b/src/modules/events/components/PurchaseTicketDialog.vue
index a1737fb..3f2dd66 100644
--- a/src/modules/events/components/PurchaseTicketDialog.vue
+++ b/src/modules/events/components/PurchaseTicketDialog.vue
@@ -298,12 +298,16 @@ const isFiatPending = ref(false);
 const fiatError = ref<string | null>(null);
 
 const enabledRails = computed(() =>
-  effectivePaymentMethods({
-    // Fiat is a per-wave opt-in; `event.allow_fiat` is only the primary
-    // wave's and can disagree with the tier being bought.
-    allowFiat: pricing.value.allow_fiat,
-    paymentMethods: props.event.payment_methods,
-  }),
+  effectivePaymentMethods(
+    {
+      allowFiat: props.event.allow_fiat,
+      paymentMethods: props.event.payment_methods,
+    },
+    // Fiat is a per-wave opt-in, and the organiser's explicit rail list is
+    // event-level — without the wave here the dialog offers a card button
+    // the purchase endpoint then refuses.
+    pricing.value,
+  ),
 );
 const canChooseFiat = computed(() => enabledRails.value.includes("fiat"));
 const isPriceInSats = computed(
diff --git a/src/modules/events/components/TicketWavesEditor.vue b/src/modules/events/components/TicketWavesEditor.vue
index 0812886..b152176 100644
--- a/src/modules/events/components/TicketWavesEditor.vue
+++ b/src/modules/events/components/TicketWavesEditor.vue
@@ -27,6 +27,12 @@ const props = defineProps<{
   knownIds?: string[];
   /** Currency of the primary wave; new rows inherit it. */
   currency?: string;
+  /** Whether the event accepts fiat, and in what. New rows inherit both so
+   *  the in-memory row is right before saving; on save the dialog applies
+   *  the event-level Card checkbox to every wave anyway, which is why
+   *  there is no per-wave switch here — it would be overwritten. */
+  allowFiat?: boolean;
+  fiatCurrency?: string;
   disabled?: boolean;
 }>();
 const emit = defineEmits<{ "update:modelValue": [waves: TicketWave[]] }>();
@@ -47,7 +53,11 @@ function update(index: number, patch: Partial<TicketWave>) {
 function add() {
   emit("update:modelValue", [
     ...props.modelValue,
-    newWaveRow({ currency: props.currency ?? "sat" }),
+    newWaveRow({
+      currency: props.currency ?? "sat",
+      allow_fiat: props.allowFiat ?? false,
+      fiat_currency: props.fiatCurrency ?? "USD",
+    }),
   ]);
 }
 
diff --git a/src/modules/events/lib/paymentMethods.spec.ts b/src/modules/events/lib/paymentMethods.spec.ts
index 72c80f2..1991ef1 100644
--- a/src/modules/events/lib/paymentMethods.spec.ts
+++ b/src/modules/events/lib/paymentMethods.spec.ts
@@ -1,21 +1,79 @@
-import { describe, it, expect } from 'vitest'
-import { effectivePaymentMethods } from './paymentMethods'
+import { describe, it, expect } from "vitest";
+import { effectivePaymentMethods } from "./paymentMethods";
 
-describe('effectivePaymentMethods', () => {
-  it('falls back to the legacy allowFiat rule when no list is published', () => {
-    expect(effectivePaymentMethods({ allowFiat: false })).toEqual(['lightning'])
-    expect(effectivePaymentMethods({ allowFiat: true })).toEqual(['lightning', 'fiat'])
-    expect(effectivePaymentMethods(undefined)).toEqual(['lightning'])
-  })
+describe("effectivePaymentMethods", () => {
+  it("falls back to the legacy allowFiat rule when no list is published", () => {
+    expect(effectivePaymentMethods({ allowFiat: false })).toEqual([
+      "lightning",
+    ]);
+    expect(effectivePaymentMethods({ allowFiat: true })).toEqual([
+      "lightning",
+      "fiat",
+    ]);
+    expect(effectivePaymentMethods(undefined)).toEqual(["lightning"]);
+  });
 
-  it('honours an explicit list, including fiat-only events', () => {
-    expect(effectivePaymentMethods({ allowFiat: true, paymentMethods: ['fiat'] })).toEqual(['fiat'])
-    expect(effectivePaymentMethods({ allowFiat: false, paymentMethods: ['lightning', 'fiat'] }))
-      .toEqual(['lightning', 'fiat'])
-  })
+  it("honours an explicit list, including fiat-only events", () => {
+    expect(
+      effectivePaymentMethods({ allowFiat: true, paymentMethods: ["fiat"] }),
+    ).toEqual(["fiat"]);
+    expect(
+      effectivePaymentMethods({
+        allowFiat: false,
+        paymentMethods: ["lightning", "fiat"],
+      }),
+    ).toEqual(["lightning", "fiat"]);
+  });
 
-  it('drops unknown rails and falls back when nothing known remains', () => {
-    expect(effectivePaymentMethods({ allowFiat: false, paymentMethods: ['onchain'] })).toEqual(['lightning'])
-    expect(effectivePaymentMethods({ allowFiat: false, paymentMethods: ['onchain', 'fiat'] })).toEqual(['fiat'])
-  })
-})
+  it("drops unknown rails and falls back when nothing known remains", () => {
+    expect(
+      effectivePaymentMethods({
+        allowFiat: false,
+        paymentMethods: ["onchain"],
+      }),
+    ).toEqual(["lightning"]);
+    expect(
+      effectivePaymentMethods({
+        allowFiat: false,
+        paymentMethods: ["onchain", "fiat"],
+      }),
+    ).toEqual(["fiat"]);
+  });
+});
+
+describe("effectivePaymentMethods — per-wave fiat", () => {
+  const railsOn = { allowFiat: true, paymentMethods: ["lightning", "fiat"] };
+
+  it("drops card for a wave that cannot take fiat", () => {
+    // Reported from aio-demo: event fiat on, Card offered, purchase
+    // refused with "Fiat payments are not enabled for this ticket wave".
+    expect(effectivePaymentMethods(railsOn, { allow_fiat: false })).toEqual([
+      "lightning",
+    ]);
+  });
+
+  it("keeps card for a wave that can", () => {
+    expect(effectivePaymentMethods(railsOn, { allow_fiat: true })).toEqual([
+      "lightning",
+      "fiat",
+    ]);
+  });
+
+  it("treats an unset wave flag as no fiat — it is how the backend reads it", () => {
+    expect(effectivePaymentMethods(railsOn, {})).toEqual(["lightning"]);
+  });
+
+  it("leaves the event-level question unfiltered", () => {
+    expect(effectivePaymentMethods(railsOn)).toEqual(["lightning", "fiat"]);
+    expect(effectivePaymentMethods(railsOn, null)).toEqual([
+      "lightning",
+      "fiat",
+    ]);
+  });
+
+  it("filters the legacy allowFiat path too", () => {
+    expect(
+      effectivePaymentMethods({ allowFiat: true }, { allow_fiat: false }),
+    ).toEqual(["lightning"]);
+  });
+});
diff --git a/src/modules/events/lib/paymentMethods.ts b/src/modules/events/lib/paymentMethods.ts
index 70e08e9..1b73b5e 100644
--- a/src/modules/events/lib/paymentMethods.ts
+++ b/src/modules/events/lib/paymentMethods.ts
@@ -1,6 +1,6 @@
-export type PaymentRailId = 'lightning' | 'fiat'
+export type PaymentRailId = "lightning" | "fiat";
 
-const KNOWN_RAILS: PaymentRailId[] = ['lightning', 'fiat']
+const KNOWN_RAILS: PaymentRailId[] = ["lightning", "fiat"];
 
 /**
  * Rails a buyer may use for an event.
@@ -13,10 +13,31 @@ const KNOWN_RAILS: PaymentRailId[] = ['lightning', 'fiat']
  */
 export function effectivePaymentMethods(
   info: { allowFiat?: boolean; paymentMethods?: string[] } | null | undefined,
+  /** The wave being bought. Omit for the event-level question ("which
+   *  rails did the organiser enable at all"). */
+  wave?: { allow_fiat?: boolean } | null,
 ): PaymentRailId[] {
   const explicit = (info?.paymentMethods ?? []).filter(
     (m): m is PaymentRailId => (KNOWN_RAILS as string[]).includes(m),
-  )
-  if (explicit.length > 0) return explicit
-  return info?.allowFiat ? ['lightning', 'fiat'] : ['lightning']
+  );
+  const rails =
+    explicit.length > 0
+      ? explicit
+      : info?.allowFiat
+        ? (["lightning", "fiat"] as PaymentRailId[])
+        : (["lightning"] as PaymentRailId[]);
+
+  // Fiat is a PER-WAVE opt-in, while the rail list above is event-level.
+  // Asking about a specific wave means asking what a buyer can actually
+  // use for it, so drop a rail that wave cannot honour — otherwise the
+  // dialog renders a card button that `api_ticket_create` refuses with
+  // "Fiat payments are not enabled for this ticket wave".
+  //
+  // A separate argument rather than reusing `info.allowFiat`: that one is
+  // the EVENT's legacy flag and means something different. The backend
+  // keeps the same split (`effective_payment_methods(event, wave)`).
+  if (wave && wave.allow_fiat !== true) {
+    return rails.filter((m) => m !== "fiat");
+  }
+  return rails;
 }
diff --git a/src/modules/events/lib/ticketWaves.spec.ts b/src/modules/events/lib/ticketWaves.spec.ts
index ce2bad2..c827510 100644
--- a/src/modules/events/lib/ticketWaves.spec.ts
+++ b/src/modules/events/lib/ticketWaves.spec.ts
@@ -327,3 +327,66 @@ describe("the primary-wave write-through a create/edit form performs", () => {
     expect(waves[1]).toEqual(REGULAR);
   });
 });
+
+describe("newWaveRow — fiat inheritance", () => {
+  it("defaults to no fiat, matching what the backend stores", () => {
+    expect(newWaveRow().allow_fiat).toBe(false);
+  });
+
+  it("inherits the event settings when the editor passes them", () => {
+    // Without this a wave created on a fiat-enabled event silently refuses
+    // card payments, and the organiser has no way to see why.
+    const row = newWaveRow({
+      allow_fiat: true,
+      fiat_currency: "EUR",
+      currency: "EUR",
+    });
+    expect(row.allow_fiat).toBe(true);
+    expect(row.fiat_currency).toBe("EUR");
+  });
+});
+
+describe("the Card checkbox governs every wave", () => {
+  // The webapp has one event-level fiat control, so on save it is applied
+  // to all waves. Pinned because getting it wrong is silent: the event
+  // reads as fiat-enabled while a wave refuses card payments, and the
+  // buyer only finds out at checkout.
+  const applyEventFiat = (
+    waves: TicketWave[],
+    acceptsFiat: boolean,
+    cur: string,
+  ) =>
+    waves.map((w) => ({ ...w, allow_fiat: acceptsFiat, fiat_currency: cur }));
+
+  const waves = [
+    wave({ id: "primary", allow_fiat: true, fiat_currency: "EUR" }),
+    wave({ id: "early", allow_fiat: false, fiat_currency: "GBP" }),
+    wave({ id: "late", allow_fiat: false, fiat_currency: "GBP" }),
+  ];
+
+  it("ticking Card enables fiat on every wave, not just the primary", () => {
+    const out = applyEventFiat(waves, true, "EUR");
+    expect(out.map((w) => w.allow_fiat)).toEqual([true, true, true]);
+    expect(out.map((w) => w.fiat_currency)).toEqual(["EUR", "EUR", "EUR"]);
+  });
+
+  it("unticking Card disables it on every wave", () => {
+    expect(
+      applyEventFiat(waves, false, "EUR").map((w) => w.allow_fiat),
+    ).toEqual([false, false, false]);
+  });
+
+  it("overwrites a stale wave fiat currency with the event's", () => {
+    // Waves created before this carry the backend's "GBP" default even on
+    // a EUR event, which is what demo showed.
+    const out = applyEventFiat(waves, true, "EUR");
+    expect(out.every((w) => w.fiat_currency === "EUR")).toBe(true);
+  });
+
+  it("leaves everything else about each wave alone", () => {
+    const [, early] = applyEventFiat(waves, true, "EUR");
+    expect(early.id).toBe("early");
+    expect(early.price_per_ticket).toBe(waves[1].price_per_ticket);
+    expect(early.amount_tickets).toBe(waves[1].amount_tickets);
+  });
+});
diff --git a/src/modules/events/lib/ticketWaves.ts b/src/modules/events/lib/ticketWaves.ts
index 9c2e710..11ad8b4 100644
--- a/src/modules/events/lib/ticketWaves.ts
+++ b/src/modules/events/lib/ticketWaves.ts
@@ -289,6 +289,14 @@ export function newWaveRow(defaults: Partial<TicketWave> = {}): TicketWave {
     // unlimited (aiolabs/events#34).
     amount_tickets: 1,
     price_per_ticket: 0,
+    // Fiat is a PER-WAVE opt-in. A wave created without it cannot take
+    // card payments however the event-level toggle is set, and the
+    // organiser gets "Fiat payments are not enabled for this ticket wave"
+    // at checkout with no way to see why. Callers pass the event's
+    // setting so a new wave inherits it, the way the LNbits admin dialog
+    // seeds one from the primary wave.
+    allow_fiat: false,
+    fiat_currency: "USD",
     ...defaults,
   };
 }