The deposit ledger
Track a tenant's security deposit separately from monthly rent, from receipt to return.
Tracking the deposit
A rental's deposit is tracked separately from the monthly payment ledger: record when it was received and the amount, and later, when the lease ends, record its return (in full, partially withheld, or fully withheld) with a note on why, if applicable. This keeps a clear record independent of monthly rent activity, which matters if there's ever a dispute about it.