Reagan’s “trickle-down” approach is usually tied to the Economic Recovery Tax Act of 1981 , so the practical answer is 1981 , during the first year of his presidency.

What that means

The phrase “trickle-down economics” was mostly a criticism of Reagan’s broader Reaganomics program, not an official policy name he used himself. The core idea was that cutting taxes, especially at the top end, would encourage investment and growth that would then spread through the economy.

Why people cite 1981

The 1981 tax law is the clearest starting point because it launched major reductions in tax rates and business tax incentives. Reagan also campaigned on this general supply-side direction before taking office, but the actual implementation began after inauguration.

TL;DR

  • When: 1981.
  • How: Through the Economic Recovery Tax Act.
  • Why it matters: That’s the policy most people mean when they say Reagan “implemented trickle-down economics”.