Under a multi-entity arrangment (holding company) is each entity
responsible for filing a separate tax return (i.e., corporation,
s-corp, or llc)including the holding company?

I found this while researching business taxes at <a
href="http://www.businesstaxrecovery.com">Business Tax Recovery</a>.
"A return must be filed for each entity since each one is considered unique.
Depending upon your arrangement, each should have a distinct tax
identification number.
If a single owner LLC is involved, the IRS will consider it a disregarded
entity and taxes should be prepared as though the entity is a sole
proprietorship."

I found this while researching business taxes at www.businesstaxrecovery.com.
"A return must be filed for each entity since each one is considered unique.
Depending upon your arrangement, each should have a distinct tax
identification number.
If a single owner LLC is involved, the IRS will consider it a disregarded
entity and taxes should be prepared as though the entity is a sole
proprietorship."

Ordinarily a group of entities with the requisite ownership
percentages can elect to file a consolidate federal tax return.  The
return is filed in the name of the holding company, and the subsidiary
companies income/loss are combined with in the other companies in the
group.

happytobeme

Yes, All companies under IRS regulations must file a tax return, no
matter the structure.