Process for preparing alkyl methacrylate, preferably methyl methacrylate, comprising a. the reacting of acetone cyanohydrin and sulfuric acid in one or more reactors I in a first reaction stage (amidation) at a temperature in the range from 70 to 130°C to obtain a first reaction mixture comprising sulfoxyisobutyramide and methacrylamide; b. the converting of the first reaction mixture, comprising heating to a temperature in the range from 130 to 200°C in one or more reactors II in a second reaction stage (conversion) to obtain a second reaction mixture comprising predominantly methacrylamide and sulfuric acid; c. the reacting of the second reaction mixture with alcohol and water, preferably methanol and water, in one or more reactors III in a third reaction stage (esterification) to obtain a third reaction mixture comprising alkyl methacrylate; d. and the separating of alkyl methacrylate from the third reaction mixture obtained from the third reaction stage; wherein the sulfuric acid used in the first reaction stage has a concentration in the range from 98.0% by weight to 100.0% by weight; wherein the separation of alkyl methacrylate from the third reaction mixture comprises at least two distillation steps in which the methacrylonitrile and acetone by-products are obtained at least partly in the tops fraction as a water-containing heteroazeotrope, wherein the water-containing heteroazeotrope comprising methacrylonitrile and acetone from at least one of these distillation steps is at least partly discharged from the process, and wherein at least one stream comprising methacrylonitrile and acetone is at least partly recycled into the third reaction stage. a. the reacting of acetone cyanohydrin and sulfuric acid in one or more reactors I in a first reaction stage (amidation) at a temperature in the range from 70 to 130°C to obtain a first reaction mixture comprising sulfoxyisobutyramide and methacrylamide; b. the converting of the first reaction mixture, comprising heating to a temperature in the range from 130 to 200°C in one or more reactors II in a second reaction stage (conversion) to obtain a second reaction mixture comprising predominantly methacrylamide and sulfuric acid; c. the reacting of the second reaction mixture with alcohol and water, preferably methanol and water, in one or more reactors III in a third reaction stage (esterification) to obtain a third reaction mixture comprising alkyl methacrylate; d. and the separating of alkyl methacrylate from the third reaction mixture obtained from the third reaction stage; wherein the sulfuric acid used in the first reaction stage has a concentration in the range from 98.0% by weight to 100.0% by weight; wherein the separation of alkyl methacrylate from the third reaction mixture comprises at least two distillation steps in which the methacrylonitrile and acetone by-products are obtained at least partly in the tops fraction as a water-containing heteroazeotrope, wherein the water-containing heteroazeotrope comprising methacrylonitrile and acetone from at least one of these distillation steps is at least partly discharged from the process, and wherein at least one stream comprising methacrylonitrile and acetone is at least partly recycled into the third reaction stage.