You can use relativedelta :
In [135]: k=2 t1 + pd.datetools.relativedelta(months=k) Out[135]: Timestamp('2013-06-01 00:00:00')
Or DateOffset :
In [136]: k=2 t1 + pd.DateOffset(months=k) Out[136]: Timestamp('2013-06-01 00:00:00')
Thanks to @AlexRiley for the proposed editing, relativedelta been moved to
pd.offsets.relativedelta since 0.20.0
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