diff --git a/packages/auth/src/Domain/UseCase/AcceptSharedSubscriptionInvitation/AcceptSharedSubscriptionInvitation.spec.ts b/packages/auth/src/Domain/UseCase/AcceptSharedSubscriptionInvitation/AcceptSharedSubscriptionInvitation.spec.ts
index a8df4f600..ae5ee3302 100644
--- a/packages/auth/src/Domain/UseCase/AcceptSharedSubscriptionInvitation/AcceptSharedSubscriptionInvitation.spec.ts
+++ b/packages/auth/src/Domain/UseCase/AcceptSharedSubscriptionInvitation/AcceptSharedSubscriptionInvitation.spec.ts
@@ -65,7 +65,7 @@ describe('AcceptSharedSubscriptionInvitation', () => {
 
     inviteeSubscription = { endsAt: 3, planName: SubscriptionName.PlusPlan } as jest.Mocked<UserSubscription>
 
-    inviterSubscription = { endsAt: 3, planName: SubscriptionName.PlusPlan } as jest.Mocked<UserSubscription>
+    inviterSubscription = { endsAt: 3, planName: SubscriptionName.PlusPlan, userUuid: '456' } as jest.Mocked<UserSubscription>
 
     userSubscriptionRepository = {} as jest.Mocked<UserSubscriptionRepositoryInterface>
     userSubscriptionRepository.findBySubscriptionIdAndType = jest.fn().mockReturnValue([inviterSubscription])
@@ -114,8 +114,8 @@ describe('AcceptSharedSubscriptionInvitation', () => {
   })
 
   it('should create a shared subscription upon accepting the invitation if inviter has a second subscription', async () => {
-    const inviterSubscription1 = { endsAt: 1, planName: SubscriptionName.PlusPlan } as jest.Mocked<UserSubscription>
-    const inviterSubscription2 = { endsAt: 5, planName: SubscriptionName.PlusPlan } as jest.Mocked<UserSubscription>
+    const inviterSubscription1 = { endsAt: 1, planName: SubscriptionName.PlusPlan, userUuid: '456' } as jest.Mocked<UserSubscription>
+    const inviterSubscription2 = { endsAt: 5, planName: SubscriptionName.PlusPlan, userUuid: '456' } as jest.Mocked<UserSubscription>
 
     timer.getTimestampInMicroseconds = jest.fn().mockReturnValue(3)
 
@@ -208,6 +208,25 @@ describe('AcceptSharedSubscriptionInvitation', () => {
     expect(applyDefaultSubscriptionSettings.execute).not.toHaveBeenCalled()
   })
 
+  it('should not create a shared subscription if invitee is the inviter', async () => {
+    inviterSubscription = { endsAt: 3, planName: SubscriptionName.PlusPlan, userUuid: '123' } as jest.Mocked<UserSubscription>
+    userSubscriptionRepository.findBySubscriptionIdAndType = jest.fn().mockReturnValue([inviterSubscription])
+
+    expect(
+      await createUseCase().execute({
+        sharedSubscriptionInvitationUuid: '1-2-3',
+      }),
+    ).toEqual({
+      success: false,
+      message: 'You cannot accept a subscription invitation sent to yourself.',
+    })
+
+    expect(sharedSubscriptionInvitationRepository.save).not.toHaveBeenCalled()
+    expect(userSubscriptionRepository.save).not.toHaveBeenCalled()
+    expect(roleService.addUserRoleBasedOnSubscription).not.toHaveBeenCalled()
+    expect(applyDefaultSubscriptionSettings.execute).not.toHaveBeenCalled()
+  })
+
   it('should not create a shared subscription if inviter subscription is not found', async () => {
     userSubscriptionRepository.findBySubscriptionIdAndType = jest.fn().mockReturnValue([])
     expect(
@@ -226,8 +245,8 @@ describe('AcceptSharedSubscriptionInvitation', () => {
   })
 
   it('should not create a shared subscription if inviter subscriptions are not active', async () => {
-    const inviterSubscription1 = { endsAt: 1, planName: SubscriptionName.PlusPlan } as jest.Mocked<UserSubscription>
-    const inviterSubscription2 = { endsAt: 2, planName: SubscriptionName.PlusPlan } as jest.Mocked<UserSubscription>
+    const inviterSubscription1 = { endsAt: 1, planName: SubscriptionName.PlusPlan, userUuid: '456' } as jest.Mocked<UserSubscription>
+    const inviterSubscription2 = { endsAt: 2, planName: SubscriptionName.PlusPlan, userUuid: '456' } as jest.Mocked<UserSubscription>
 
     timer.getTimestampInMicroseconds = jest.fn().mockReturnValue(3)
 
diff --git a/packages/auth/src/Domain/UseCase/AcceptSharedSubscriptionInvitation/AcceptSharedSubscriptionInvitation.ts b/packages/auth/src/Domain/UseCase/AcceptSharedSubscriptionInvitation/AcceptSharedSubscriptionInvitation.ts
index 70af840e5..a4ac05a0d 100644
--- a/packages/auth/src/Domain/UseCase/AcceptSharedSubscriptionInvitation/AcceptSharedSubscriptionInvitation.ts
+++ b/packages/auth/src/Domain/UseCase/AcceptSharedSubscriptionInvitation/AcceptSharedSubscriptionInvitation.ts
@@ -74,6 +74,13 @@ export class AcceptSharedSubscriptionInvitation implements UseCaseInterface {
     }
     const inviterUserSubscription = activeUserSubscriptions[0]
 
+    if (invitee.uuid === inviterUserSubscription.userUuid) {
+      return {
+        success: false,
+        message: 'You cannot accept a subscription invitation sent to yourself.',
+      }
+    }
+
     sharedSubscriptionInvitation.status = InvitationStatus.Accepted
     sharedSubscriptionInvitation.updatedAt = this.timer.getTimestampInMicroseconds()
 
diff --git a/packages/auth/src/Domain/UseCase/InviteToSharedSubscription/InviteToSharedSubscription.spec.ts b/packages/auth/src/Domain/UseCase/InviteToSharedSubscription/InviteToSharedSubscription.spec.ts
index e97871cf5..4ba150f48 100644
--- a/packages/auth/src/Domain/UseCase/InviteToSharedSubscription/InviteToSharedSubscription.spec.ts
+++ b/packages/auth/src/Domain/UseCase/InviteToSharedSubscription/InviteToSharedSubscription.spec.ts
@@ -58,6 +58,38 @@ describe('InviteToSharedSubscription', () => {
     domainEventFactory.createEmailRequestedEvent = jest.fn().mockReturnValue({} as jest.Mocked<EmailRequestedEvent>)
   })
 
+  it('should not create an invitation if user invites themselves', async () => {
+    expect(
+      await createUseCase().execute({
+        inviteeIdentifier: 'inviter@test.te',
+        inviterUuid: '1-2-3',
+        inviterEmail: 'inviter@test.te',
+        inviterRoles: [RoleName.NAMES.ProUser],
+      }),
+    ).toEqual({
+      success: false,
+    })
+
+    expect(sharedSubscriptionInvitationRepository.save).not.toHaveBeenCalled()
+    expect(domainEventFactory.createSharedSubscriptionInvitationCreatedEvent).not.toHaveBeenCalled()
+    expect(domainEventPublisher.publish).not.toHaveBeenCalled()
+  })
+
+  it('should not create an inivitation if user invites themselves with different email casing', async () => {
+    expect(
+      await createUseCase().execute({
+        inviteeIdentifier: 'Inviter@Test.TE',
+        inviterUuid: '1-2-3',
+        inviterEmail: 'inviter@test.te',
+        inviterRoles: [RoleName.NAMES.ProUser],
+      }),
+    ).toEqual({
+      success: false,
+    })
+
+    expect(sharedSubscriptionInvitationRepository.save).not.toHaveBeenCalled()
+  })
+
   it('should not create an inivitation for sharing the subscription if inviter has no subscription', async () => {
     userSubscriptionRepository.findOneByUserUuid = jest.fn().mockReturnValue(null)
 
diff --git a/packages/auth/src/Domain/UseCase/InviteToSharedSubscription/InviteToSharedSubscription.ts b/packages/auth/src/Domain/UseCase/InviteToSharedSubscription/InviteToSharedSubscription.ts
index 77c8edbc6..2952e3632 100644
--- a/packages/auth/src/Domain/UseCase/InviteToSharedSubscription/InviteToSharedSubscription.ts
+++ b/packages/auth/src/Domain/UseCase/InviteToSharedSubscription/InviteToSharedSubscription.ts
@@ -45,6 +45,16 @@ export class InviteToSharedSubscription implements UseCaseInterface {
       }
     }
 
+    const inviteeIdentifierType = this.isInviteeIdentifierPotentiallyAPrivateUsernameAccount(dto.inviteeIdentifier)
+      ? InviteeIdentifierType.Hash
+      : InviteeIdentifierType.Email
+
+    if (this.isSelfInvite(dto.inviteeIdentifier, dto.inviterEmail, inviteeIdentifierType)) {
+      return {
+        success: false,
+      }
+    }
+
     const numberOfUsedInvites = await this.sharedSubscriptionInvitationRepository.countByInviterEmailAndStatus(
       dto.inviterEmail,
       [InvitationStatus.Sent, InvitationStatus.Accepted],
@@ -69,11 +79,7 @@ export class InviteToSharedSubscription implements UseCaseInterface {
     sharedSubscriptionInvition.inviterIdentifier = dto.inviterEmail
     sharedSubscriptionInvition.inviterIdentifierType = InviterIdentifierType.Email
     sharedSubscriptionInvition.inviteeIdentifier = dto.inviteeIdentifier
-    sharedSubscriptionInvition.inviteeIdentifierType = this.isInviteeIdentifierPotentiallyAPrivateUsernameAccount(
-      dto.inviteeIdentifier,
-    )
-      ? InviteeIdentifierType.Hash
-      : InviteeIdentifierType.Email
+    sharedSubscriptionInvition.inviteeIdentifierType = inviteeIdentifierType
     sharedSubscriptionInvition.status = InvitationStatus.Sent
     sharedSubscriptionInvition.subscriptionId = inviterUserSubscription.subscriptionId as number
     sharedSubscriptionInvition.createdAt = this.timer.getTimestampInMicroseconds()
@@ -110,4 +116,16 @@ export class InviteToSharedSubscription implements UseCaseInterface {
   private isInviteeIdentifierPotentiallyAPrivateUsernameAccount(identifier: string): boolean {
     return identifier.length === 64 && !identifier.includes('@')
   }
+
+  private isSelfInvite(
+    inviteeIdentifier: string,
+    inviterEmail: string,
+    inviteeIdentifierType: InviteeIdentifierType,
+  ): boolean {
+    if (inviteeIdentifierType !== InviteeIdentifierType.Email) {
+      return false
+    }
+
+    return inviteeIdentifier.trim().toLowerCase() === inviterEmail.trim().toLowerCase()
+  }
 }