diff --git a/server/src/db/database.ts b/server/src/db/database.ts
index 499e900d6..09d0cdb3e 100644
--- a/server/src/db/database.ts
+++ b/server/src/db/database.ts
@@ -129,11 +129,12 @@ function getPlaceWithTags(placeId: number | string): PlaceWithTags | null {
 interface TripAccess {
   id: number;
   user_id: number;
+  currency: string | null;
 }
 
 function canAccessTrip(tripId: number | string, userId: number): TripAccess | undefined {
   return db.prepare(`
-    SELECT t.id, t.user_id FROM trips t
+    SELECT t.id, t.user_id, t.currency FROM trips t
     LEFT JOIN trip_members m ON m.trip_id = t.id AND m.user_id = ?
     WHERE t.id = ? AND (t.user_id = ? OR m.user_id IS NOT NULL)
   `).get(userId, tripId, userId) as TripAccess | undefined;
diff --git a/server/src/nest/budget/budget.controller.ts b/server/src/nest/budget/budget.controller.ts
index 4a1c3e631..1ea0be54b 100644
--- a/server/src/nest/budget/budget.controller.ts
+++ b/server/src/nest/budget/budget.controller.ts
@@ -64,7 +64,7 @@ export class BudgetController {
     @Query('base') base?: string,
   ) {
     const trip = this.requireTrip(tripId, user);
-    return this.budget.settlement(tripId, base, (trip as { currency?: string }).currency || 'EUR');
+    return this.budget.settlement(tripId, base, trip.currency || 'EUR');
   }
 
   @Get('settlements')
diff --git a/server/tests/unit/db/trip-access.test.ts b/server/tests/unit/db/trip-access.test.ts
new file mode 100644
index 000000000..a24cfc2e0
--- /dev/null
+++ b/server/tests/unit/db/trip-access.test.ts
@@ -0,0 +1,54 @@
+/**
+ * canAccessTrip is the shared trip-access check every domain reads its trip row
+ * from. It must return the trip's `currency`: the budget settlement takes its base
+ * currency straight off this row, and when the column was missing from the SELECT
+ * it silently fell back to 'EUR', inflating balances on every non-EUR trip that had
+ * a foreign-currency expense (#1543).
+ */
+import { describe, it, expect, beforeEach } from 'vitest';
+import { db, canAccessTrip } from '../../../src/db/database';
+
+function seedUser(username: string): number {
+  return Number(
+    db.prepare("INSERT INTO users (username, email, password_hash, role) VALUES (?, ?, 'x', 'user')")
+      .run(username, `${username}@example.test`).lastInsertRowid,
+  );
+}
+
+describe('canAccessTrip', () => {
+  beforeEach(() => {
+    db.exec('DELETE FROM trip_members; DELETE FROM trips; DELETE FROM users;');
+  });
+
+  it('returns the trip currency for the owner (#1543)', () => {
+    const owner = seedUser('owner');
+    const tripId = Number(
+      db.prepare("INSERT INTO trips (user_id, title, currency) VALUES (?, 'Trip', 'RUB')")
+        .run(owner).lastInsertRowid,
+    );
+
+    expect(canAccessTrip(tripId, owner)).toMatchObject({ id: tripId, user_id: owner, currency: 'RUB' });
+  });
+
+  it('returns the trip currency for a member too', () => {
+    const owner = seedUser('owner2');
+    const member = seedUser('member2');
+    const tripId = Number(
+      db.prepare("INSERT INTO trips (user_id, title, currency) VALUES (?, 'Trip', 'JPY')")
+        .run(owner).lastInsertRowid,
+    );
+    db.prepare('INSERT INTO trip_members (trip_id, user_id) VALUES (?, ?)').run(tripId, member);
+
+    expect(canAccessTrip(tripId, member)).toMatchObject({ currency: 'JPY' });
+  });
+
+  it('returns undefined for a user with no access', () => {
+    const owner = seedUser('owner3');
+    const stranger = seedUser('stranger3');
+    const tripId = Number(
+      db.prepare("INSERT INTO trips (user_id, title) VALUES (?, 'Trip')").run(owner).lastInsertRowid,
+    );
+
+    expect(canAccessTrip(tripId, stranger)).toBeUndefined();
+  });
+});