BUG: Breaking change to offsets.pyx - quarter offset classes

doc/source/reference/offset_frequency.rst

@@ -655,7 +655,7 @@ Properties
     BQuarterEnd.normalize
     BQuarterEnd.rule_code
     BQuarterEnd.n
-    BQuarterEnd.startingMonth
+    BQuarterEnd.month
 
 Methods
 ~~~~~~~
@@ -690,7 +690,7 @@ Properties
     BQuarterBegin.normalize
     BQuarterBegin.rule_code
     BQuarterBegin.n
-    BQuarterBegin.startingMonth
+    BQuarterBegin.month
 
 Methods
 ~~~~~~~
@@ -725,7 +725,7 @@ Properties
     QuarterEnd.normalize
     QuarterEnd.rule_code
     QuarterEnd.n
-    QuarterEnd.startingMonth
+    QuarterEnd.month
 
 Methods
 ~~~~~~~
@@ -760,7 +760,7 @@ Properties
     QuarterBegin.normalize
     QuarterBegin.rule_code
     QuarterBegin.n
-    QuarterBegin.startingMonth
+    QuarterBegin.month
 
 Methods
 ~~~~~~~

doc/source/whatsnew/v0.18.0.rst

@@ -686,6 +686,7 @@ when it is an anchor point (e.g., a quarter start date), and otherwise roll
 forward to the next anchor point.
 
 .. ipython:: python
+   :okwarning:
 
    d = pd.Timestamp('2014-02-01')
    d
@@ -706,6 +707,7 @@ This behavior has been corrected in version 0.18.0, which is consistent with
 other anchored offsets like ``MonthBegin`` and ``YearBegin``.
 
 .. ipython:: python
+   :okwarning:
 
    d = pd.Timestamp('2014-02-15')
    d + pd.offsets.QuarterBegin(n=0, startingMonth=2)

doc/source/whatsnew/v1.3.0.rst

@@ -458,6 +458,36 @@ with a :class:`MultiIndex` in the result. This can lead to a perceived duplicati
     df.groupby('label1').rolling(1).sum()
 
 
+.. _whatsnew_130.notable_bug_fixes.quarterbegin_default_anchor:
+
+Changed default periods in :class:`~pandas.tseries.offsets.QuarterBegin` and :class:`~pandas.tseries.offsets.BQuarterBegin`
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Quarter-based time offset classes :class:`~pandas.tseries.offsets.QuarterEnd`,
+:class:`~pandas.tseries.offsets.QuarterBegin`, :class:`~pandas.tseries.offsets.BQuarterEnd`,
+:class:`~pandas.tseries.offsets.BQuarterBegin` now use ``month`` instead of ``startingMonth``
+as a time anchor parameter (:issue:`5307`). The default value for :class:`~pandas.tseries.offsets.QuarterBegin`
+and :class:`~pandas.tseries.offsets.BQuarterBegin` is now 1 (January) instead of 3 (March),
+as a result these offsets are aligned with standard calendar quarters (:issue:`8435`).
+
+*pandas 1.2.x*
+
+.. code-block:: ipython
+
+   In [1]: pd.Timestamp(2014, 10, 10) + pd.tseries.offsets.QuarterBegin()
+   Out[2]: Timestamp('2014-12-01 00:00:00')
+   In [3]: pd.Timestamp(2014, 10, 10) + pd.tseries.offsets.BQuarterBegin()
+   Out[4]: Timestamp('2014-12-01 00:00:00')
+
+*pandas 1.3.0*
+
+.. code-block:: ipython
+
+   In [1]: pd.Timestamp(2014, 10, 10) + pd.tseries.offsets.QuarterBegin()
+   Out[2]: Timestamp('2015-01-01 00:00:00')
+   In [3]: pd.Timestamp(2014, 10, 10) + pd.tseries.offsets.BQuarterBegin()
+   Out[4]: Timestamp('2015-01-01 00:00:00')
+
 .. _whatsnew_130.api_breaking.deps:
 
 Increased minimum versions for dependencies
@@ -570,6 +600,7 @@ Deprecations
 - Deprecated allowing partial failure in :meth:`Series.transform` and :meth:`DataFrame.transform` when ``func`` is list-like or dict-like and raises anything but ``TypeError``; ``func`` raising anything but a ``TypeError`` will raise in a future version (:issue:`40211`)
 - Deprecated support for ``np.ma.mrecords.MaskedRecords`` in the :class:`DataFrame` constructor, pass ``{name: data[name] for name in data.dtype.names}`` instead (:issue:`40363`)
 - Deprecated the use of ``**kwargs`` in :class:`.ExcelWriter`; use the keyword argument ``engine_kwargs`` instead (:issue:`40430`)
+- Deprecated the ``startingMonth`` keyword in quarter-based offsets :class:`QuarterBegin`, :class:`QuarterEnd`, :class:`BQuarterBegin`, :class:`BQuarterEnd`; use ``month`` instead (:issue:`5307`)
 - Deprecated the ``level`` keyword for :class:`DataFrame` and :class:`Series` aggregations; use groupby instead (:issue:`39983`)
 
 .. ---------------------------------------------------------------------------
@@ -625,6 +656,7 @@ Datetimelike
 - Bug in :meth:`Timedelta.round`, :meth:`Timedelta.floor`, :meth:`Timedelta.ceil` for values near the implementation bounds of :class:`Timedelta` (:issue:`38964`)
 - Bug in :func:`date_range` incorrectly creating :class:`DatetimeIndex` containing ``NaT`` instead of raising ``OutOfBoundsDatetime`` in corner cases (:issue:`24124`)
 - Bug in :func:`infer_freq` incorrectly fails to infer 'H' frequency of :class:`DatetimeIndex` if the latter has a timezone and crosses DST boundaries (:issue:`39556`)
+- Bug in offsets :class:`QuarterBegin` and :class:`BQuarterBegin` returning days that are not conventional quarter beginnings (:issue:`8435`)
 
 Timedelta
 ^^^^^^^^^