The Catholic Church teaches that scripture is sufficient.

The Catholic Church teaches that scripture is sufficient. But Protestants and Catholic will defer on what they mean by sufficiency of scripture. A Protestant would say that scripture is “formally sufficient” while a Catholic would say that scripture is “materially sufficient”.

 Let me define these two terms:

1. Materially Sufficient- scripture contains or implies all that is needed for salvation.
2. Formally Sufficient – scripture contains all the data of material sufficiency, but scripture is so clear that it does not need any outside information to interpret it.

So sola scriptura, as argued during the reformation, is that scripture is formally sufficient for deciding all matters of Christian doctrine and practice.

Therefore,formal sufficiency must be proven from scripture alone that is that scripture is so clear that no outside information or authority is needed in order to correctly interpret scripture and an inspired interpretive grid must be provided from within the pages of scripture.
From The Catholic Catechism:


73 God has revealed himself fully by sending his own Son, in whom he has established his covenant forever. The Son is his Father's definitive Word; so there will be no further Revelation after him.

76 In keeping with the Lord's command, the Gospel was handed on in two ways: - orally "by the apostles who handed on, by the spoken word of their preaching, by the example they gave, by the institutions they established, what they themselves had received - whether from the lips of Christ, from his way of life and his works, or whether they had learned it at the prompting of the Holy Spirit"; - in writing "by those apostles and other men associated with the apostles who, under the inspiration of the same Holy Spirit, committed the message of salvation to writing".

107 The inspired books teach the truth. "Since therefore all that the inspired authors or sacred writers affirm should be regarded as affirmed by the Holy Spirit, we must acknowledge that the books of Scripture firmly, faithfully, and without error teach that truth which God, for the sake of our salvation, wished to see confided to the Sacred Scriptures." inspired books teach the truth. should be regarded as affirmed by the Holy Spirit, we must acknowledge that the books of Scripture firmly, faithfully, and without error teach that truth which God, for the sake of our salvation, wished to see confided to the Sacred Scriptures.