"statement showing the state of credits and debits in a particular business," 1812, from balance (n.) in the accounting sense + sheet (n.1).
Entries linking to balance-sheet
balance n.
early 13c., "scales, apparatus for weighing by comparison of mass," from Old French balance "balance, scales for weighing" (12c.), also in figurative sense; from Medieval Latin bilancia, from Late Latin bilanx, from Latin (libra) bilanx "(scale) having two pans," possibly from Latin bis "twice" (from PIE root *dwo- "two") + lanx "dish, plate, scale of a balance," which is of uncertain origin.
The accounting sense "arithmetical difference between the two sides of an account" is from 1580s; the meaning "sum necessary to balance the two sides of an account" is from 1620s. The meaning "what remains or is left over" is by 1788, originally in commercial slang. The sense of "physical equipoise" is from 1660s; that of "general harmony between parts" is from 1732.
Many figurative uses are from the Middle English image of the scales in the hands of personified Justice, Fortune, Fate, etc.; thus in (the) balance "at risk, in jeopardy or danger" (c. 1300). Balance of power in the geopolitical sense "distribution of forces among nations so that one may not dominate another" is from 1701. Balance of trade "difference between the value of exports from a country and the value of imports into it" is from 1660s.
sheet n.1
[length of cloth] Old English sciete (West Saxon), scete (Mercian) "length of cloth, covering, napkin, towel, shroud," according to Watkins from Proto-Germanic *skautjon-, with notions of "corner," from *skauta- "project" (source also of Old Norse skaut, Gothic skauts "seam, hem of a garment;" Dutch schoot; German Schoß "bosom, lap"), from PIE root *skeud- "to shoot, chase, throw." "A very abstract and uncertain semantic development" according to Boutkan (who rightly can't resist adding a German assessment of it, etwas hervorragendes).
It is attested by mid-13c. as "large square or rectangular piece of linen or cotton spread over a bed next to the sleeper." The sense of "oblong or square piece of paper," especially one suitable for writing or printing on, is recorded by c. 1500; that of "any broad, flat, relatively thin surface" (of metal, open water, etc.) is from 1590s. Of a continuous sweep of falling rain from 1690s. The meaning "a newspaper" is recorded by 1749.
Sheet lightning, caused by cloud reflection, is attested from 1794; sheet music is from 1857. Between the sheets "in bed" (usually with sexual overtones) is attested from 1590s (played upon in "Much Ado"); to be white as a sheet is from 1751. The first element in sheet-anchor (late 15c.), one used only in emergencies, appears to be a different word, of unknown origin, perhaps with some connection to shoot (v.) on the notion of being "shot out."