tert-Butyl amino(diethoxyphosphoryl)acetate (2a) is prepared on a multigram scale from tert-butyl diethoxyphosphorylacetate (1a) in a facile two-step synthesis. The method involves the formation of diazo derivative 4 and subsequent catalytic hydrogenation. Compound 2a is also synthesized by reduction of the oxime derivative 3. Direct amination of diethoxyphosphorylacetic esters with chloramine gives other types of esters 2b-e in addition to the tert-butyl ester 2a.