Welcome to the Community, Shanice.
The error message "taxReturnInvalidMTDEndDate" occurs when you attempt to submit a VAT return too early or if your Making Tax Digital (MTD) permissions haven’t been fully activated.
To resolve this issue, make sure the tax period has officially ended before attempting to submit your VAT return. Additionally, double-check that your QuickBooks Online (QBO) is digitally authorised to file VAT returns with HMRC.
In QBO, open the All Apps menu and select VAT to verify your MTD connection. Then, sign in to your HMRC account to confirm that your VAT account is enrolled for MTD.
If you have follow-up questions, feel free to reach out.
