Being an Executor of an Estate or a Trustee of a Trust comes with having fiduciary responsibility to the ultimate beneficiaries. One such responsibility is to provide an accounting: a report of all the revenue and expenses.
There are several instances where an accounting might be done:
Usually, the Executor or a Trustee will provide an informal accounting prior to making the final distribution from the Estate or the Trust. As part of this process, the Executor or Trustee will ask the beneficiary to sign a Release and Waiver Agreement, designed to protect the Executor or Trustee from liability.
Sometimes, the beneficiaries may request an accounting.