This thesis explores the benefits of tax loss harvesting by examining the time period from 1999-2000 to determine the potential profits investors could realize from utilizing this strategy. The first step to accomplishing this was to collect data from the past 20-plus years from the SPDR S&P 500 Exchange Traded Fund (SPY) and its 11 sectors: Energy (XLE), Consumer Staples (XLP), Consumer Discretionary (XLY), Communication Services (XLC), Real Estate (XLRE), Technology (XLK), Utilities (XLU), Materials (XLB), Industrials (XLI), Financials (XLF), and Health Care (XLV). The next step was to clean the data from hundreds of months of opening prices, closing prices, and quarterly dividends into an annual opening price and total annual dividends to calculate a rate of return. Finally, I found the weightings of the S&P 500 and its sectors on January 1st of every year and input this data into a model whose output reflected the growth of a portfolio with and without the use of tax loss harvesting. Once this model was created, I determined the benefits of tax loss harvesting in the present and the value of carrying these losses forward. The outcomes of this thesis solely reflect the benefits of using tax loss harvesting through a passive investment strategy. This research will enrich academic and professional understandings of tax loss harvesting through its clear demonstration of how much tax loss carryforward can be accessed, as well as the opportunity for gains from compounding interest on previous tax savings due to tax loss harvesting.