Nev. Rev. Stat. § 99.040

1. When there is no express contract in writing fixing a different rate of interest, interest must be allowed at a rate equal to the prime rate at the largest bank in Nevada, as ascertained by the Commissioner of Financial Institutions, on January 1 or July 1, as the case may be, immediately preceding the date of the transaction, plus 2 percent, upon all money from the time it becomes due, in the following cases: (a) Upon contracts, express or implied, other than book accounts. (b) Upon the settlement of book or store accounts from the day on which the balance is ascertained. (c) Upon money received to the use and benefit of another and detained without his or her consent. (d) Upon wages or salary, if it is unpaid when due, after demand therefor has been made. The rate must be adjusted accordingly on each January 1 and July 1 thereafter until the judgment is satisfied.

2. The provisions of this section do not apply to money owed pursuant to chapter 624 of NRS which is governed by the provisions of NRS 624.630 .

3. As used in this section, “ book account ” means a detailed statement which: (a) Constitutes the principal record of one or more transactions between a debtor and a creditor arising out of a contract or some fiduciary relationship; (b) Shows the debits and credits in connection with that contract or fiduciary relationship and shows against whom and in favor of whom entries are made; (c) Is entered in the regular course of business as conducted by such creditor or fiduciary; and (d) Is kept in a reasonably permanent form and manner: (1) In a bound book; (2) On a sheet or sheets fastened in a book or to backing but detachable therefrom; (3) On a card or cards of a permanent character; or (4) In any other reasonably permanent form and manner.