The only disadvantage, sort of, is at tax time. When you fill out the business tax form there is a section dealing with calculating COGS, basically it amounts to starting inventory value, + purchases – end inventory value

as you said you do not have inventory, so for taxes that value […]

Resolution for 'business COGS issue: 'Can I categorize parts that are sold as job supplies?' available: Yes.

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

For more information about resolving issues related to business COGS in Quickbooks/QBO or to get support for the issue 'Can I categorize parts that are sold as job supplies?', click the link below: