I have found that Active Directory already supports multi-tenancy within a domain.
Make certain that applicationName
setting in your web.config is the same for your Sharepoint and MVC apps.
<membership>
<providers>
<clear/>
<add
name="MyADMembershipProvider"
type="System.Web.Security.ActiveDirectoryMembershipProvider, System.Web,
Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
connectionStringName="ADConnectionString"
.......
applicationName="/"
/>
</providers>
</membership>