Because each task uses far more computing power than a normal reply, Deep Research is rationed on every plan. As of September 2026, OpenAI lists it as limited on the Free and Go plans, expanded on Plus at $20 per month, and at its highest allowance on Pro. OpenAI no longer publishes exact monthly task counts, and Deep Research run inside ChatGPT Work draws on that product's separate allowance.
Beyond usage caps, Deep Research has practical limits. It can only read what is publicly accessible or what you give it, so paywalled journals, subscription databases, and private sources are usually out of reach. Even with citations, it can occasionally misattribute a claim or summarize a source inaccurately, which is why important findings should always be checked against the original.
Time is the other trade-off. A task that takes 20 minutes is fine for a market report, but it is the wrong tool when you need a fast answer, and spending a limited monthly allowance on simple questions leaves less for the research that actually needs it.