diff --git a/frontend/src/components/admin/group/GroupRateMultipliersModal.vue b/frontend/src/components/admin/group/GroupRateMultipliersModal.vue
index efeb95e0e3..dfcd238f30 100644
--- a/frontend/src/components/admin/group/GroupRateMultipliersModal.vue
+++ b/frontend/src/components/admin/group/GroupRateMultipliersModal.vue
@@ -426,7 +426,7 @@ const updateLocalRate = (userId: number, value: string) => {
     return
   }
   const num = parseFloat(value)
-  if (isNaN(num)) return
+  if (!Number.isFinite(num) || num <= 0) return
   entry.rate_multiplier = num
 }
 
diff --git a/frontend/src/components/admin/group/__tests__/GroupRateMultipliersModal.edit.spec.ts b/frontend/src/components/admin/group/__tests__/GroupRateMultipliersModal.edit.spec.ts
new file mode 100644
index 0000000000..e1fc6c557c
--- /dev/null
+++ b/frontend/src/components/admin/group/__tests__/GroupRateMultipliersModal.edit.spec.ts
@@ -0,0 +1,52 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { enableAutoUnmount, flushPromises, mount } from '@vue/test-utils'
+import type { AdminGroup } from '@/types'
+import GroupRateMultipliersModal from '../GroupRateMultipliersModal.vue'
+
+const mocks = vi.hoisted(() => ({ getGroupRateMultipliers: vi.fn(), batchSetGroupRateMultipliers: vi.fn() }))
+vi.mock('@/api/admin', () => ({ adminAPI: { groups: mocks } }))
+vi.mock('@/stores/app', () => ({ useAppStore: () => ({ showSuccess: vi.fn(), showError: vi.fn() }) }))
+vi.mock('vue-i18n', () => ({ useI18n: () => ({ t: (key: string) => key }) }))
+enableAutoUnmount(afterEach)
+beforeEach(() => {
+  vi.resetAllMocks()
+  mocks.getGroupRateMultipliers.mockResolvedValue([
+    { user_id: 7, user_email: 'user@example.com', user_name: '', user_status: 'active', rate_multiplier: 2, rpm_override: null }
+  ])
+})
+
+async function openEditor() {
+  const wrapper = mount(GroupRateMultipliersModal, {
+    props: { show: false, group: { id: 1, name: 'Group', platform: 'openai', rate_multiplier: 1 } as AdminGroup },
+    global: { stubs: {
+      BaseDialog: { props: ['show'], template: '<div v-if="show"><slot /></div>' },
+      Icon: true, PlatformIcon: true, Pagination: true
+    } }
+  })
+  await wrapper.setProps({ show: true })
+  await flushPromises()
+  return wrapper
+}
+
+describe('group rate multiplier edits', () => {
+  it.each(['0', '-1'])('does not stage invalid custom rate %s', async (value) => {
+    const wrapper = await openEditor()
+    await wrapper.get('tbody input[type="number"]').setValue(value)
+    expect(wrapper.findAll('button').some(button => button.text() === 'common.save')).toBe(false)
+    expect(mocks.batchSetGroupRateMultipliers).not.toHaveBeenCalled()
+  })
+
+  it.each([['0.5', 0.5], ['1e-3', 0.001]])('saves positive rate %s', async (value, expected) => {
+    const wrapper = await openEditor()
+    await wrapper.get('tbody input[type="number"]').setValue(value)
+    await wrapper.findAll('button').find(button => button.text() === 'common.save')!.trigger('click')
+    expect(mocks.batchSetGroupRateMultipliers).toHaveBeenCalledWith(1, [{ user_id: 7, rate_multiplier: expected }])
+  })
+
+  it('still removes an override when its input is cleared', async () => {
+    const wrapper = await openEditor()
+    await wrapper.get('tbody input[type="number"]').setValue('')
+    await wrapper.findAll('button').find(button => button.text() === 'common.save')!.trigger('click')
+    expect(mocks.batchSetGroupRateMultipliers).toHaveBeenCalledWith(1, [])
+  })
+})