"Cash outlay" refers to the amount of money that needs to be spent or paid out as an expense for something. It is the total cost of purchasing or investing in a product, service, or project. Full definition
Trade Credit allows a business to better match the timing of cash outlays for the cost of goods sold with the cash receipts from sales. (perfectcreditagain.com)
In the example of a Toronto - Calgary flight, Aeroplan miles have decreased in value as they have increased the amount of cash outlay required to redeem the flight. (creditwalk.ca)
So since it's giving you a CoC ROI of 9.89 %, it must be assuming an initial cash outlay of -LRB-($ 281.73 x 12) / 0.0989) = $ 34,183.62. (biggerpockets.com)