ser = pd.Series([pd.Timestamp('2000-1-1'), pd.Timestamp('2000-2-1')]) other = pd.Series([pd.offsets.DateOffset(years=1), pd.offsets.MonthEnd()]) >>> ser + other 0 2001-01-01 1 2000-02-29 dtype: datetime64[ns] >>> other + ser Traceback (most recent call last): File "<stdin>", line 1, in <module> File "pandas/core/ops.py", line 698, in wrapper result = wrap_results(safe_na_op(lvalues, rvalues)) File "pandas/core/ops.py", line 665, in safe_na_op lambda x: op(x, rvalues)) File "pandas/_libs/algos_common_helper.pxi", line 1212, in pandas._libs.algos.arrmap_object result[i] = func(index[i]) File "pandas/core/ops.py", line 665, in <lambda> lambda x: op(x, rvalues)) File "pandas/tseries/offsets.py", line 352, in __add__ return self.apply(other) File "pandas/tseries/offsets.py", line 77, in wrapper result = func(self, other) File "pandas/tseries/offsets.py", line 212, in apply other = other + self._offset TypeError: ufunc add cannot use operands with types dtype('<M8[ns]') and dtype('O')