The pope isnt infallible ever. Hes just a man, human, totally fallible and sinful like all humans. Catholucs delude themselves - or the papacy and catholic hierarchy delude them - with these blasphemous lies.
21 But now the righteousness of God apart from the law is revealed, being witnessed by the Law and the Prophets, 22 even the righteousness of God, through faith in Jesus Christ, to all and on all who believe. For there is no difference; 23 for all have sinned and fall short of the glory of God, 24 being justified freely by His grace through the redemption that is in Christ Jesus, 25 whom God set forth as a propitiation by His blood, through faith, to demonstrate His righteousness, because in His forbearance God had passed over the sins that were previously committed, 26 to demonstrate at the present time His righteousness, that He might be just and the justifier of the one who has faith in Jesus.
I'm not sure whether or not he retains infallibility when he retires. However, many people here seem to misunderstand how the pope is infallible. Contrary to what the people above think, the pope is not "totally infallible." His infallibility extends only to matters of faith and morals, and it can operate only when he is defining something pertaining to faith or morals for the whole church. Infallibility is a special gift God gave to the Church to protect it from teaching as true what is, in fact, false. It is a special protection to ensure that the Faith will not be distorted by error. (My answer continues in the comments)
Man of Knowledge has given an excellent explanation of papal infallibility; but to answer your question, when Benedict XVI's resignation becomes effective, at 8:00 P.M., on February 28, 2013, Rome time, he will no longer be Pope, so will no longer be infallible, as an individual, but he will share in the infallibility, of all of the Bishops, when they act with and under (Latin: cum et sub) the Pope, to teach the whole Church, in any matter of faith or morals, which happened most recently during the Second Ecumenical Vatican Council (Vatican Council II), 1962-1965, which means that it was the second such council to take place, in the Vatican, at Rome, Italy, specifically, in the Sistine Chapel, where Michelangelo Bonarati's famous paintings adorn the ceiling. I hope this helps to fully answer your question. Frank P.S. When only some of the Bishops so act with and under the Pope, as during a Synod, they act under his infallibility, not their own. Frank
Being a member of the human race makes every person fallible and subject to error. Being in a position or office is no promise or guarantee of infallibility. A simple examination of RC history proves that (e.g. indulgences). A simple examination of the Jewish Pharisees, the religious authorities of their time also shows the danger of thinking position means infallible. Jesus revealed their hypocrisy and error in moral issues and teaching on numerous occasions. Man is not, and never has been, infallible.
It is so ironic that the very doctrine of papal infallibility is a clear example of fallibility. That doctrine is responsible for so much error, it is tragic. Talk about fallibility--that is it. That is why James said "not many of you should presume to be teachers, knowing they will face stricter judgment." Yes, we will be all be held accountable for how we handle God's Word.