# Locks
Peach ensures consistency of the loan's ledger and balances. In order to make sure that
multiple operations are not writing to the ledger at the same time, Peach uses locks to protect
the consistency of the loan.
In situations where an API call affects a loan's ledger, the system will lock the
loan to protect its consistency. Subsequent calls that affect that loan's ledger might
return a `423 Locked` status if the loan is still locked. In these cases, you can make
a call to <a href="/api-docs/api-public/loans/peach.people.loans.handlers.get_lock_status">Lock Status</a>
to check if the loan is still locked.
If you are trying to make a call and get `423 Locked`, consider polling on the <a href="/api-docs/api-public/loans/peach.people.loans.handlers.get_lock_status">Lock Status</a>
to check when the lock is released. Most locks are short.
Some API calls (e.g. retroactive interest adjustment or payment backdate)
can trigger a loan replay. Loan replays can last several minutes, during which the loan will
be locked.