Hi,

The issue you're encountering with HMRC VAT submissions is likely due to the annual changes in HMRC's VAT API, which can break existing integrations unless the relevant addons, like Odoo's UK-Accounting Reports module, are updated. To resolve this, ensure that you're using the latest version of the addon, as HMRC's VAT API is updated every year. If you're using older addons, they may not be compatible with the latest HMRC changes.

Hope it helps.