There's no direct way to turn on 20% RC for the Construction Industry Scheme (CIS) in the QuickBooks Online (QBO) Mobile App, asareinforcement. However, you can enable this feature by accessing your account through a web browser.
Before we proceed, could you please clarify what you mean by RC? This will help me provide you with the most accurate solution.
In the meantime, here's how to enable the CIS through a web browser.
- Sign in to your QBO account through a web browser.
- Go to the Gear icon at the top right corner, then select Account and Settings.
- Navigate to the Advanced tab.
- Click Construction Industry Scheme (CIS).
- Enter your UTR no., Employer’s PAYE reference no., and Accounts Office reference no..
- If you’re a CIS subcontractor, tick the box labeled I am a CIS subcontractor and select your deduction rate from the dropdown menu.
- Select Save, then Done.

You can always return to this thread if you have follow-up questions.