diff --git a/emis-biz/src/main/java/com/xdadan/erp/emis/service/impl/EmisSettleBillServiceImpl.java b/emis-biz/src/main/java/com/xdadan/erp/emis/service/impl/EmisSettleBillServiceImpl.java
index c5cf4adbd..d1a07a79f 100644
--- a/emis-biz/src/main/java/com/xdadan/erp/emis/service/impl/EmisSettleBillServiceImpl.java
+++ b/emis-biz/src/main/java/com/xdadan/erp/emis/service/impl/EmisSettleBillServiceImpl.java
@@ -1608,6 +1608,63 @@ public class EmisSettleBillServiceImpl extends EmisBaseService implements IEmisS
     @Override
     public int updateEmisSettleBill(EmisSettleBill emisSettleBill)
     {
+        // 如果修改了billMonth，需要重新计算最后回款日
+        if (emisSettleBill.getId() != null && StringUtils.isNotEmpty(emisSettleBill.getBillMonth())) {
+            EmisSettleBill oldBill = emisSettleBillMapper.selectEmisSettleBillById(emisSettleBill.getId());
+            if (oldBill != null && !emisSettleBill.getBillMonth().equals(oldBill.getBillMonth())) {
+                // billMonth发生变化，且是月结类型，需要重新计算最后回款日
+                if ("2".equals(oldBill.getSettleType())) {
+                    EmisCustomerUser monthUser = getCustomerUserByMonthlyPayCode(oldBill.getCustNo());
+                    if (monthUser != null) {
+                        // 默认30天，从1号开始
+                        BigDecimal creditPeriod = BigDecimal.valueOf(30D);
+                        Integer settleDay = 1;
+
+                        if (monthUser.getCreditPeriod() != null) {
+                            creditPeriod = monthUser.getCreditPeriod();
+                        }
+
+                        if (monthUser.getSettleDay() != null) {
+                            settleDay = monthUser.getSettleDay();
+                        }
+
+                        Date paymentDueDate = null;
+                        // 周结和半月结的特殊处理
+                        if (creditPeriod.intValue() == 7) {
+//                            // 获取今日零点 T+6,T为出账日
+//                            String currDayStr = DateUtils.parseDateToStr(DateUtils.YYYY_MM_DD, new Date());
+//                            Date currDayDate = DateUtils.parseDate(currDayStr);
+//                            paymentDueDate = DateUtils.addDays(currDayDate, 7);
+                        } else if (creditPeriod.intValue() == 15) {
+//                            String currDayStr = DateUtils.parseDateToStr(DateUtils.YYYY_MM_DD, new Date());
+//                            Date currDayDate = DateUtils.parseDate(currDayStr);
+//                            paymentDueDate = DateUtils.addDays(currDayDate, 15);
+                        } else {
+                            Date billMonthDate = DateUtils.parseDate(emisSettleBill.getBillMonth() + "-" + settleDay);
+
+                            // credit_period 为 30/60/90 且结算日为每月 1 号时，按对应月份月末作为最后付款日
+                            if ((creditPeriod.intValue() == 30 || creditPeriod.intValue() == 60 || creditPeriod.intValue() == 90)
+                                    && monthUser.getSettleDay() == 1) {
+                                Calendar cal = Calendar.getInstance();
+                                cal.setTime(billMonthDate);
+                                // 30 -> 加 1 个月，60 -> 加 2 个月，90 -> 加 3 个月
+                                cal.add(Calendar.MONTH, creditPeriod.intValue() / 30);
+                                // 设置为该月的最后一天
+                                cal.set(Calendar.DAY_OF_MONTH, cal.getActualMaximum(Calendar.DAY_OF_MONTH));
+                                paymentDueDate = cal.getTime();
+                            } else {
+                                paymentDueDate = DateUtils.addMonths(billMonthDate, 1);
+                                paymentDueDate = DateUtils.addDays(paymentDueDate, creditPeriod.intValue());
+                            }
+                        }
+
+                        // 设置重新计算后的最后回款日
+                        emisSettleBill.setPaymentDueDate(paymentDueDate);
+                    }
+                }
+            }
+        }
+
         return emisSettleBillMapper.updateEmisSettleBill(emisSettleBill);
     }