Error message
Accounting period is not defined in the period date table in Exact Online.Affected ERP integrations
Exact Online
Cause
This error occurs when the document date or service period of the expense being exported from Payhawk corresponds to an accounting period that has not yet been defined in Exact Online's period date table. Without a defined accounting period for the relevant date, Exact Online cannot process or post the transaction.
Solution
To resolve this issue:
Log in to your Exact Online account.
Navigate to Master Data > Financial > Period-date table.
Review the list of defined accounting periods and identify the period that corresponds to the document date or service period of the expense in Payhawk.
If the required period is missing, add a new accounting period that covers the relevant date range.
Click Save.

Return to Payhawk and attempt to export the expense again. The export must now be successful.
To prevent this error in the future, ensure that your Exact Online period date table is kept up to date with all relevant accounting periods, particularly at the start of a new financial year when new periods will need to be created.