That is correct, you do need to register as a foreign entity if the company is registered abroad.
Whether an entity is domestic or foreign does not depend on the location of the principal business office. Instead, it depends on where the entity was formed and what law governs its internal affairs. If an organization was formed under, and the internal affairs are governed by, the laws of a jurisdiction other than Texas, the organization is a “foreign entity.” We sometimes refer to foreign entities as out-of-state entities to reinforce the concept that entities formed in other U.S. states are foreign entities, as well as entities formed outside of the United States.
The fee is $750:
This is the penalty if you don't:
A foreign entity that has transacted business in Texas for more than ninety days without registering is subject to a late filing fee. The
late filing fee is equal to the registration fee for each full or
partial calendar year that the foreign entity transacted business in
Texas without being registered.
Have you considered forming a separate entity in Texas from scratch or does it need to be associated with the company formed abroad?
For the exemptions specified in the law, see: http://www.statutes.legis.state.tx.us/Docs/BO/htm/BO.9.htm
SUBCHAPTER F. DETERMINATION OF TRANSACTING BUSINESS IN THIS STATE
Sec. 9.251. ACTIVITIES NOT CONSTITUTING TRANSACTING BUSINESS IN THIS STATE. For purposes of this chapter, activities that do not constitute transaction of business in this state include:
(1) maintaining or defending an action or suit or an administrative or arbitration proceeding, or effecting the settlement of:
(A) such an action, suit, or proceeding; or
(B) a claim or dispute to which the entity is a party;
(2) holding a meeting of the entity's managerial officials, owners, or members or carrying on another activity concerning the entity's internal affairs;
(3) maintaining a bank account;
(4) maintaining an office or agency for:
(A) transferring, exchanging, or registering securities the entity issues; or
(B) appointing or maintaining a trustee or depositary related to the entity's securities;
(5) voting the interest of an entity the foreign entity has acquired;
(6) effecting a sale through an independent contractor;
(7) creating, as borrower or lender, or acquiring indebtedness or a mortgage or other security interest in real or personal property;
(8) securing or collecting a debt due the entity or enforcing a right in property that secures a debt due the entity;
(9) transacting business in interstate commerce;
(10) conducting an isolated transaction that:
(A) is completed within a period of 30 days; and
(B) is not in the course of a number of repeated, similar transactions;
(11) in a case that does not involve an activity that would constitute the transaction of business in this state if the activity were one of a foreign entity acting in its own right:
(A) exercising a power of executor or administrator of the estate of a nonresident decedent under ancillary letters issued by a court of this state; or
(B) exercising a power of a trustee under the will of a nonresident decedent, or under a trust created by one or more nonresidents of this state, or by one or more foreign entities;
(12) regarding a debt secured by a mortgage or lien on real or personal property in this state:
(A) acquiring the debt in a transaction outside this state or in interstate commerce;
(B) collecting or adjusting a principal or interest payment on the debt;
(C) enforcing or adjusting a right or property securing the debt;
(D) taking an action necessary to preserve and protect the interest of the mortgagee in the security; or
(E) engaging in any combination of transactions described by this subdivision;
(13) investing in or acquiring, in a transaction outside of this state, a royalty or other nonoperating mineral interest;
(14) executing a division order, contract of sale, or other instrument incidental to ownership of a nonoperating mineral interest; or
(15) owning, without more, real or personal property in this state.