Definition
Systematic investigation is the structured, planned approach to resolving a scientific or technological uncertainty that HMRC expects to see evidenced in a qualifying R&D project. Although not a stand-alone statutory term, the concept is drawn from the BIS Guidelines' requirement that the work actually seeks to resolve the uncertainty. Evidence typically includes project plans, hypotheses, experimental designs, results logs, decision records and post-activity reviews. Ad hoc trial-and-error without recorded method is a common area of HMRC challenge.
How HMRC defines it
HMRC's expectation of systematic investigation is reflected at CIRD81300 and in the 2024 Guidelines for Compliance GfC3, Help to see if your work qualifies as R&D for tax purposes. The guidance provides specific examples of the kinds of records HMRC expects and distinguishes structured R&D from ad hoc product iteration.
Practical example
A materials company seeking to develop a new composite documents its hypothesis, the designed factorial experiment, the measured outcomes and the conclusions. A peer company iterates informally, with no designed experiments or recorded results. HMRC finds the first project easier to accept as genuine R&D on audit because the systematic investigation is documented.