Origin and history of tasker

early 14c., taske, "a quantity of labor imposed as a duty," from Old North French tasque (12c., Old French tasche, Modern French tâche) "duty, tax," from Vulgar Latin *tasca "a duty, assessment," a metathesis of Medieval Latin taxa, which is a back-formation from Latin taxare "to evaluate, estimate, assess" (see tax (v.)). A doublet of tax (n.); also compare taste.

The general sense of "any piece of work that has to be done" is recorded by 1590s. Also in Middle English as "a tax" (c. 1400); this is obsolete but the phrase take (one) to task (1680s) preserves a sense that is closer to tax.

German Tasche "pocket" is from the same Vulgar Latin source (via Old High German tasca), with presumable sense evolution from "amount of work imposed by some authority," to "payment for that work," to "wages," to "pocket into which money is put," to "any pocket."

"overseer, one whose office is to impose burdens with labor and see to their doing," 1520s, from task (n.) + master (n.). Task-lord also was used. Task-mistress is attested from c. 1600. Tasker is from 1580s as "imposer of tasks" (earlier "one who threshes with a flail;" mid-13c. as a surname).