To create an adhoc accrual you start by clicking the + Add accrual button in the top right corner of the summary or schedule page:
This will open a modal where you can provide the details of the accrual and let us know if it should be adhoc or recurring:
Adhoc accruals create a one off entry of the amount provided on the accrue date.
Note: If you do not yet know when the accrual should be reversed you can leave the reversal date empty. See this article for more details.