# Corporation Tax Act 2009, Paragraph 121


(1) In relation to expenditure incurred before 27 September 2003, section 1124 applies, for the purposes of Chapters 2 and 7 of Part 13, with the modification in sub-paragraph (3).
(2) In relation to expenditure incurred before 9 April 2003, section 1124 applies, for the purposes of Chapters 3 to 5 of Part 13, with the modification in sub-paragraph (3).
(3) For subsections (3) and (4) substitute—
“(3) In the case of a director (“D”) or employee (“E”) partly engaged directly and actively in relevant research and development the following rules apply—
(a) if the time D or E spends so engaged is less than 20% of D's or E's total working time, none of the staffing costs relating to D or E is treated as attributable to relevant research and development,
(b) if the time D or E spends so engaged is more than 80% of D's or E's total working time, the whole of the staffing costs relating to D or E is treated as attributable to relevant research and development,
(c) in any other case, an appropriate proportion of the staffing costs relating to D or E is treated as attributable to relevant research and development.”

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Source: https://www.legislation.gov.uk/ukpga/2009/4/schedule/2/paragraph/121 (the official version)
Page: https://openlegislation.uk/corporation-tax-act-2009/schedule-2/paragraph-121
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.