Add days to dates in dataframe

If I understand you, you don’t actually want shift, you simply want to make a new column next to the existing DATE which is 180 days after. In that case, you can use timedelta:

>>> from datetime import timedelta
>>> df.head()
                                 ID                DATE
8  0103bd73af66e5a44f7867c0bb2203cc 2001-02-01 00:00:00
0  002691c9cec109e64558848f1358ac16 2003-08-13 00:00:00
1  002691c9cec109e64558848f1358ac16 2003-08-13 00:00:00
5  00d34668025906d55ae2e529615f530a 2006-03-09 00:00:00
4  00d34668025906d55ae2e529615f530a 2006-03-09 00:00:00
>>> df["X_DATE"] = df["DATE"] + timedelta(days=180)
>>> df.head()
                                 ID                DATE              X_DATE
8  0103bd73af66e5a44f7867c0bb2203cc 2001-02-01 00:00:00 2001-07-31 00:00:00
0  002691c9cec109e64558848f1358ac16 2003-08-13 00:00:00 2004-02-09 00:00:00
1  002691c9cec109e64558848f1358ac16 2003-08-13 00:00:00 2004-02-09 00:00:00
5  00d34668025906d55ae2e529615f530a 2006-03-09 00:00:00 2006-09-05 00:00:00
4  00d34668025906d55ae2e529615f530a 2006-03-09 00:00:00 2006-09-05 00:00:00

Does that help any?