Would there be any reason that we could not charge a processing fee on home equity LINES of credit?

It's not an "authorized" fee in the Texas Finance Code...therefore it would be considered "unauthorized." That's how I understand it, but I don't claim to be an expert.

Yes, that is how I understood it too, but wanted to make sure. When I said that we aren't authorized to charge that, the question was asked if we could charge an origination fee then. I think we can (based on reference in attorney materials I have referring to a 1981 letter from the Office of the Consumer Credit Commission), but you have to add it with all of the other interest and charges to make sure the "yield to the lender" doesn't exceed the allowable interest rate at the time the loan was made. What does that mean exactly? Does it mean the APR when including that fee cannot exceed 18%?

Thank you in advance for your patience and help on this.

There's no restriction on an APR. The loan rate, however, cannot exceed 18%. The origination fee because it is considered to be a pre-paid finance charge, bumps the APR. The origination fee is a fee that must be included in the 3% fee cap. As to how to figure the "yield to the lender," I'm clueless. I agree with you that an origination fee is an authorized fee.