What is one way to begin saving startup capital?

On september 1, 2016, steve loaned brett $2,000 at 12% interest compounded annually. steve is not in the business of lending money. the note stated that principal and interest would be due on august 31, 2018. in 2018, steve received $2,508.80 ($2,000 principal and $508.80 interest). steve uses the cash method of accounting. what amount must steve include in income on his income tax return?