No. Using a plan manager doesn't reduce your NDIS funding at all.
When you ask for plan management at your planning meeting or reassessment, the NDIA adds separate funding to your plan specifically to pay your plan manager. It's completely separate from the funding for your supports, therapies and services, so every dollar of your support budget stays yours to use.
In other words: plan management is free for you and it doesn't shrink anything else in your plan.
If you'd like plan management added to your plan, just tell your planner at your next meeting, or email us at hello@providerchoice.com.au and we'll help you ask for it.