diff --git a/src/accounting/models.py b/src/accounting/models.py
index 7cd8339..d0c88b4 100644
--- a/src/accounting/models.py
+++ b/src/accounting/models.py
@@ -203,25 +203,6 @@ class Account(db.Model):
                 return
         self.l10n.append(AccountL10n(locale=current_locale, title=value))
 
-    @property
-    def is_in_use(self) -> bool:
-        """Returns whether the account is in use.
-
-        :return: True if the account is in use, or False otherwise.
-        """
-        if not hasattr(self, "__is_in_use"):
-            setattr(self, "__is_in_use", len(self.entries) > 0)
-        return getattr(self, "__is_in_use")
-
-    @is_in_use.setter
-    def is_in_use(self, is_in_use: bool) -> None:
-        """Sets whether the account is in use.
-
-        :param is_in_use: True if the account is in use, or False otherwise.
-        :return: None.
-        """
-        setattr(self, "__is_in_use", is_in_use)
-
     @classmethod
     def find_by_code(cls, code: str) -> t.Self | None:
         """Finds an account by its code.
diff --git a/src/accounting/static/js/account-selector.js b/src/accounting/static/js/account-selector.js
index 96e2edd..69f13ad 100644
--- a/src/accounting/static/js/account-selector.js
+++ b/src/accounting/static/js/account-selector.js
@@ -140,7 +140,7 @@ class AccountSelector {
      * @return {string[]} the account codes that are used in the form
      */
     #getAccountCodeUsedInForm() {
-        const accountCodes = Array.from(document.getElementsByClassName("accounting-account-code"));
+        const accountCodes = Array.from(document.getElementsByClassName("accounting-" + this.#prefix + "-account-code"));
         const formAccount = document.getElementById("accounting-entry-form-account");
         const inUse = [formAccount.dataset.code];
         for (const accountCode of accountCodes) {
diff --git a/src/accounting/templates/accounting/transaction/include/form-entry-item.html b/src/accounting/templates/accounting/transaction/include/form-entry-item.html
index 427cf7e..8f593a2 100644
--- a/src/accounting/templates/accounting/transaction/include/form-entry-item.html
+++ b/src/accounting/templates/accounting/transaction/include/form-entry-item.html
@@ -25,7 +25,7 @@ First written: 2023/2/25
     <input type="hidden" name="currency-{{ currency_index }}-{{ entry_type }}-{{ entry_index }}-eid" value="{{ entry_id }}">
   {% endif %}
   <input id="accounting-currency-{{ currency_index }}-{{ entry_type }}-{{ entry_index }}-no" type="hidden" name="currency-{{ currency_index }}-{{ entry_type }}-{{ entry_index }}-no" value="{{ entry_index }}">
-  <input id="accounting-currency-{{ currency_index }}-{{ entry_type }}-{{ entry_index }}-account-code" class="accounting-account-code" type="hidden" name="currency-{{ currency_index }}-{{ entry_type }}-{{ entry_index }}-account_code" value="{{ account_code_data }}" data-text="{{ account_text }}">
+  <input id="accounting-currency-{{ currency_index }}-{{ entry_type }}-{{ entry_index }}-account-code" class="accounting-{{ entry_type }}-account-code" type="hidden" name="currency-{{ currency_index }}-{{ entry_type }}-{{ entry_index }}-account_code" value="{{ account_code_data }}" data-text="{{ account_text }}">
   <input id="accounting-currency-{{ currency_index }}-{{ entry_type }}-{{ entry_index }}-summary" type="hidden" name="currency-{{ currency_index }}-{{ entry_type }}-{{ entry_index }}-summary" value="{{ summary_data }}">
   <input id="accounting-currency-{{ currency_index }}-{{ entry_type }}-{{ entry_index }}-amount" class="accounting-currency-{{ currency_index }}-{{ entry_type }}-amount" type="hidden" name="currency-{{ currency_index }}-{{ entry_type }}-{{ entry_index }}-amount" value="{{ amount_data }}">
   <div class="accounting-entry-content">
diff --git a/src/accounting/transaction/forms.py b/src/accounting/transaction/forms.py
index 5faafea..184a416 100644
--- a/src/accounting/transaction/forms.py
+++ b/src/accounting/transaction/forms.py
@@ -115,6 +115,35 @@ class IsDebitAccount:
             "This account is not for debit entries."))
 
 
+class AccountOption:
+    """An account option."""
+
+    def __init__(self, account: Account):
+        """Constructs an account option.
+
+        :param account: The account.
+        """
+        self.__account: Account = account
+        self.id: str = account.id
+        self.code: str = account.code
+        self.is_in_use: bool = False
+
+    def __str__(self) -> str:
+        """Returns the string representation of the account option.
+
+        :return: The string representation of the account option.
+        """
+        return str(self.__account)
+
+    @property
+    def query_values(self) -> list[str]:
+        """Returns the values to be queried.
+
+        :return: The values to be queried.
+        """
+        return self.__account.query_values
+
+
 class JournalEntryForm(FlaskForm):
     """The base form to create or edit a journal entry."""
     eid = IntegerField()
@@ -321,40 +350,37 @@ class TransactionForm(FlaskForm):
             obj.no = count + 1
 
     @property
-    def debit_account_options(self) -> list[Account]:
+    def debit_account_options(self) -> list[AccountOption]:
         """The selectable debit accounts.
 
         :return: The selectable debit accounts.
         """
-        accounts: list[Account] = Account.debit()
-        in_use: set[int] = self.__get_in_use_account_id()
+        accounts: list[AccountOption] \
+            = [AccountOption(x) for x in Account.debit()]
+        in_use: set[int] = set(db.session.scalars(
+            sa.select(JournalEntry.account_id)
+            .filter(JournalEntry.is_debit)
+            .group_by(JournalEntry.account_id)).all())
         for account in accounts:
             account.is_in_use = account.id in in_use
         return accounts
 
     @property
-    def credit_account_options(self) -> list[Account]:
+    def credit_account_options(self) -> list[AccountOption]:
         """The selectable credit accounts.
 
         :return: The selectable credit accounts.
         """
-        accounts: list[Account] = Account.credit()
-        in_use: set[int] = self.__get_in_use_account_id()
+        accounts: list[AccountOption] \
+            = [AccountOption(x) for x in Account.credit()]
+        in_use: set[int] = set(db.session.scalars(
+            sa.select(JournalEntry.account_id)
+            .filter(sa.not_(JournalEntry.is_debit))
+            .group_by(JournalEntry.account_id)).all())
         for account in accounts:
             account.is_in_use = account.id in in_use
         return accounts
 
-    def __get_in_use_account_id(self) -> set[int]:
-        """Returns the ID of the accounts that are in use.
-
-        :return: The ID of the accounts that are in use.
-        """
-        if self.__in_use_account_id is None:
-            self.__in_use_account_id = set(db.session.scalars(
-                sa.select(JournalEntry.account_id)
-                .group_by(JournalEntry.account_id)).all())
-        return self.__in_use_account_id
-
     @property
     def currencies_errors(self) -> list[str | LazyString]:
         """Returns the currency errors, without the errors in their sub-forms.