Maintaining spending power in real terms (current) while preserving an endowment's value in real terms (future) is the crux of intergenerational equity. Tobin's (1974) model provides the conceptual basis on which simulations were developed to study the impact of various inflation (0%, TIPS, CPI, HECA, and HEPI) and new giving scenarios ($0, $4 million and $8 million) on the value of the USD Foundation endowment as well as the value of the future payouts from the endowment. All inflation scenarios except 0% inflation require new gifts to the endowment to maintain or grow the inflation-adjusted value of the endowment with a 6.85% nominal return, 4.80% payout and 2% administrative fee. With $8,000,000 in annual new gifts to the endowment, the inflation-adjusted value of the endowment grows in all five inflation scenarios. With $4,000,000 in annual new gifts to the endowment, the inflation-adjusted value of the endowment grows over time in the 0%, TIPS, and CPI inflation scenarios but declines in the higher inflation scenarios (HECA and HEPI). The level of new gifts required to provide for intergenerational equity was also determined; new giving increases the size of the payout on a dollar-for-dollar basis. Holding the sustainable payout rate constant at 4.80% and using HECA as the inflation assumption shows that the "break-even" calculation is $4,946,170 in new gifts per-year. Finally, the sustainable payout rate under the assumption of zero new gifts was determined. As expected, the sustainable payout decreases with higher inflation and is lower than the current payout rate.