The date for the writing of Galatians will depend on the decision made on the recipients and the relationship of the book to the Jerusalem Council.  Paul gives a great deal of biographical detail in the book, which ought to make determining a date a bit easier.  Alas, that is not the case!  In chapter 2 there are two incidents that may or may not be related to the Jerusalem council in Acts 15. Luke mentions three visits to Jerusalem:  the initial visit, the famine visit (11:27-30), and the 15 day visit.

In an article published in 1967, C. H. Talbert summarizes the issue into seven positions, five of which I summarize here:

1.  That Gal 2:1–10 is the Jerusalem Council visit of Acts 15:1–30; the famine visit is not mentioned by Paul in Galatians.  Why is it not mentioned?  Perhaps Paul did not meet with Apostles at that time, or perhaps it was simply to deliver the gift and no real “contact” was made.  To include it would bog down his argument in Galatians with another visit that is neither here nor there with respect to his apostolic authority.

2.  That Gal 2:1–10 is the famine visit of Acts 11:27–30, with the Jerusalem Council visit of Acts 15:1–30 taking place after Galatians was written.  A variation on this is that Gal 2:1-10 is the first visit, the famine visit is not mentioned for the same reasons as under A, and that the Council occurs after Galatians.

3.  That Gal 2:1–10 is the Jerusalem Council visit of Acts 15:1–30, which Luke has turned into two visits by misunderstanding the parallel nature of two reports he received about the council and so fabricating the visit of Acts 11:27–30.

4.  That Gal 2:1–10 is the Jerusalem Council visit of Acts 15:1–30, with Acts 11:27–30 being a misplaced report of the collection visit which was originally connected with the material of Acts 21:15–17 but which Luke has chosen to place earlier in order to support his schematic portrayal of the expansion of the church.

5.  That Gal 2:1–10 is the Jerusalem Council visit of Acts 15:1–30, with Acts 11:27–30 being an invention of Luke (for reasons given in either positions three or four above) and with the Jerusalem Council visit to be identified with the hasty visit of Acts 18:22.

The first and second options seem to be the only options that allow for Luke to be an accurate history.  Luke does not appear to be given to invention or serious error.  Why would Paul omit the trip to Jerusalem to deliver the famine relief gift?  It is really not a major problem, since the meeting to deliver the gift is not related to meeting the apostles.

Perhaps Paul went to Jerusalem many times between Acts 9 and 13 for any number of reasons.  If he had lived in Jerusalem he may have had friends and family there, possessions that needed to be collected and taken to Antioch, etc. None of these sorts of visits to the city would be important to the argument since he did not contact the Apostles and have meetings and “training sessions.”

The most difficult part of the first position above is that Paul never mentions the decision of the in the letter to the Galatians.  One would imagine that if the Judaizers claimed to be from James, Paul simply had to hold up the letter from the council and say, “Look here, the man you claim as your authority disagrees with you, go back to Jerusalem as get a bit more education on the issue of Gentiles!”  That he does not is powerful evidence the council has not yet occurred.

It seems best then to see the Jerusalem council as not appearing in Galatians, simply because it has not occurred yet. If one opts for a southern Galatian destination, then usually it is argued the book is written before the Jerusalem council, thus a date of A.D. 49.  Those that see the destination as northern Galatia typically date the book after 1 & 2 Corinthians, about the late 50’s.  The churches founded in the third missionary journey are not detailed in Acts, therefore it is difficult to know how early in the chronology of Acts to place the letter.

Bibliography:
C. H. Talbert, “Again: Paul’s Visits to Jerusalem” NovT 9 (1967) 26, n. 3.

Richard N. Longenecker, Galatians (WBC, Dallas, Word, 1990).  Longenecker discusses the five listed above, including the advocates of each position.