The "Big Beautiful Bill" has significantly altered US energy tax policy by reducing clean energy tax credit values by $500 billion over the next decade. According to Wood Mackenzie, wind and solar sectors have been most affected, as projects must begin construction by July 4, 2026, and be placed in service by 2030 to qualify for full 45Y and 48E credits. An executive order has redefined “start construction” to require substantial on-site progress, while the use of components from China, Russia, Iran, or North Korea has led to disqualification. Eligibility for battery, geothermal, and nuclear projects is retained through 2033, though Wood Mackenzie has warned that battery storage is at risk due to Chinese supply reliance. The 45U credit for existing nuclear has been preserved with FEOC limits, while 45V hydrogen credit eligibility has been shortened. Carbon capture has gained support through expanded 45Q credits. Oil, gas, and coal sectors have benefited from a delayed methane tax to 2035, expanded federal lease sales, and restored 100% bonus depreciation.