Relation between「帳」and「賬」
簡易六書原則



形聲:



在中國文字中，形聲字的比例最多，「形聲」就是形符和聲符的配合，「形符」表示字的類別；「聲符」則表示字的字音

Both 帳 and 賬 are 形聲字 (Pictophonetic characters)

貝 indicates the character is related to 'money/finance'. It is the semantic component of the character 賬

巾 indicates the character is related to 'tent/cloth'. It is the semantic component of the character 帳

長 is the phonetic component of both 帳 and 賬



張 is a 會意形聲字. [弓 = bow --&gt; bow extends + phonetic 長]

Wang_xiao_ming posted:

按：此字本為帳幕之義，後亦用為錢項計簿之義，此義或从貝作「賬」。清．翟灝《通俗編．貨財》云：「幃幄曰帳，而計簿亦曰帳者，運籌必在幃幄中也。今市井或造賬字用之，諸字書中皆未見。

It said 帳 originally meant 'tents', acquired the meaning of &quot;accounting&quot; later because &quot;運籌必在幃幄中也&quot; meaning: &quot;to calculate war strategy, one must be in a tent&quot; (in the army, close to the battlefield)
Since accounting involves money, the 巾 radical was replaced by the 貝 radical.  The meaning of 'account --&gt; (debt)' in '帳' thereafter, was transferred to '賬'.
'今市井或造賬字用之，諸字書中皆未見' However, at the beginning, 賬 was considered a made-up word by the general public, not listed in any reference book.