Texas Estates Code - EST § 351.251. Mortgage or Pledge of Estate Property Authorized in Certain Circumstances

(1) the payment of any ad valorem, income, gift, estate, inheritance, or transfer taxes on the transfer of an estate or due from a decedent or the estate, regardless of whether those taxes are assessed by a state, a political subdivision of a state, the federal government, or a foreign country;

(2) the payment of expenses of administration, including amounts necessary for operation of a business, farm, or ranch owned by the estate;

(3) the payment of claims allowed and approved, or established by suit, against the estate;  or

(4) the renewal and extension of an existing lien.