there is no mandate to install 2018.  if you are using 2017 or 2016, you can use it forever, but each year’s version is sunsetted after 3 years and you will no longer have access to payroll or online functions.

Resolution for 'before January 1 issue: 'When is the deadline for installing QuickBooks Desktop 2018? Do we have to update our software before January 1, 2018?' available: Yes.

The before January 1 issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the before January 1 issue yourself by looking for a resolution described in the article. If it is a complex before January 1 issue or you are unable to solve the issue, you may contact us by clicking here or by using other before January 1 support options.

For more information about resolving issues related to before January 1 in Quickbooks/QBO or to get support for the issue 'When is the deadline for installing QuickBooks Desktop 2018? Do we have to update our software before January 1, 2018?', click the link below: