No pensar hacer algo

[chileno]

Originally Posted by AngelicaDeAlquezar

I agree with all answers, but I'll add a little side note: "No pienso pagar" and "no pienso que (yo) pague" would be perfect equivalents, but the second one shouldn't be used because it's the same subject ("yo"); it sounds low register.

Another way to express the doubt of "I don't think I'm going to pay", without subjunctive, could be "creo/me parece que no voy a pagar".

I added that (yo) because it depends of who is being talked about or who is talking... he/she/ I right?

[AngelicaDeAlquezar]

Right, Hernán. In those cases amphibology ambiguity must be avoided by introducing a pronoun.
I only said that this sentence does not express the same idea Perikles talked about, but the one in the OP. In that case, infinitive is preferred.

[aleCcowaN]

No pienso (1. tr. Imaginar, considerar o discurrir) que pague [frase inusual]= No creo (4. tr. Tener algo por verosímil o probable) que pague

No pienso (3. tr. Intentar o formar ánimo de hacer algo.) pagar = No tengo la intención de pagar

No pueden ser más diferentes en significado frases como "ni pienso constestarle" y "no pienso que le conteste [frase inusual]"

[chileno]

Pienso y creo firmemente que el contexto dictará el uso. Quizás estoy equivocado y no sería la primera vez, ni la última.