Hello and welcome to the Community, Hugh01
After connecting QuickBooks to HMRC, you'll need to re-authorise the connection every 18 months. This is to meet HMRC's security requirements and keep your data safe.
Reauthorising is quick and easy, taking just a few moments. We'll alert you in product that you need to take action. All you'll have to do is enter your login details. After that, we'll take care of everything else.
If you don't see a prompt to re-authorise on the Tax dashboard, you can instead disconnect and re-connect MTD in QuickBooks to reset the authorisation period.
Thanks for reaching Intuit support. I'm just a post away if you have further questions or require additional assistance.