Research and development expenses tax credits. Creates a step-rate reimbursement structure for the major research and development expenses tax credit in an amount equal to (i) 10 percent, up to the first $1 million, of the difference between (a) Virginia qualified research and development expenses paid or incurred by the taxpayer during the taxable year and (b) 50 percent of the average Virginia qualified research and development expenses paid or incurred by the taxpayer for the three taxable years immediately preceding the taxable year for which the credit is being determined and (ii) five percent of such difference in excess of $1 million. Beginning in taxable year 2023, the bill also (a) imposes an annual per taxpayer major research and development expenses tax credit cap of $300,000, except that such cap increases to $400,000 if the Virginia qualified research was conducted in conjunction with a public or private institution of higher education in the Commonwealth, (b) reduces from $24 million to $16 million the aggregate cap on the major research and development expenses tax credit granted for each fiscal year, and (c) increases from $7.77 million to $15.77 million the aggregate cap on the research and development expenses tax credit granted for each fiscal year beginning in taxable year 2023.