Add dividend tax rate configuration and update StockPosition handling

- Introduced `dividend_tax_rate` configuration in `__init__.py` to support fixed tax rate for dividends.
- Updated `AccountMod` to assign `dividend_tax_rate` to `StockPosition`, ensuring proper handling of dividend taxation.
- Adjusted dividend calculation in `StockPosition` to account for the new tax rate, enhancing accuracy in financial computations.

Author: Cuizi7

rqalpha/mod/rqalpha_mod_sys_accounts/__init__.py

@@ -21,6 +21,8 @@
     "stock_t1": True,
     # 是否开启自动分红再投资
     "dividend_reinvestment": False,
+    # 红利税，暂只支持固定税率
+    "dividend_tax_rate": 0.0,
     # 当持仓股票退市时，是否按照退市价格返还现金
     "cash_return_by_stock_delisted": True,
     # 股票下单因资金不足被拒时改为使用全部剩余资金下单

rqalpha/mod/rqalpha_mod_sys_accounts/mod.py

@@ -35,6 +35,7 @@ def start_up(self, env, mod_config):
         # type: (Environment, Any) -> None
 
         StockPosition.dividend_reinvestment = mod_config.dividend_reinvestment
+        StockPosition.dividend_tax_rate = mod_config.dividend_tax_rate
         StockPosition.cash_return_by_stock_delisted = mod_config.cash_return_by_stock_delisted
         StockPosition.t_plus_enabled = mod_config.stock_t1
 

rqalpha/mod/rqalpha_mod_sys_accounts/position_model.py

@@ -51,6 +51,7 @@ class StockPosition(Position):
     __instrument_types__ = INST_TYPE_IN_STOCK_ACCOUNT
 
     dividend_reinvestment = False
+    dividend_tax_rate: float = 0.
     cash_return_by_stock_delisted = True
     t_plus_enabled = True
 
@@ -202,7 +203,7 @@ def _handle_dividend_book_closure(self, trading_date, data_proxy):
         dividends = self._get_dividends_or_splits(self._all_dividends, trading_date, "ex_dividend_date")  # type: ignore[reportIncompatibleVariableOverride]
         if dividends is None or len(dividends) == 0:
             return
-        dividend_per_share: float = (dividends["dividend_cash_before_tax"] / dividends["round_lot"]).sum()
+        dividend_per_share: float = (dividends["dividend_cash_before_tax"] / dividends["round_lot"]).sum() * (1 - self.dividend_tax_rate)
         self._avg_price -= dividend_per_share
         # 前一天结算发生了除息, 此时 last_price 还是前一个交易日的收盘价，需要改为 除息后收盘价, 否则影响在before_trading中查看盈亏
         self._last_price -= dividend_per_share  # type: ignore