2018 isn’t even out yet (usually released in September or October), but yes, unless you have the Plus subscription plan (a yearly subscription, much more costly than just purchasing outright) you pay the full price for new versions.

Resolution for 'cost attached issue: 'My quickbooks 2013 Pro is asking me to upgrade to 2018. Is there any cost attached to this?' available: Yes.

The cost attached 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 cost attached issue yourself by looking for a resolution described in the article. If it is a complex cost attached issue or you are unable to solve the issue, you may contact us by clicking here or by using other cost attached support options.

For more information about resolving issues related to cost attached in Quickbooks/QBO or to get support for the issue 'My quickbooks 2013 Pro is asking me to upgrade to 2018. Is there any cost attached to this?', click the link below: