Neb. Rev. Stat. § 21-1792

A member may receive a loan in installments or in one sum and may prepay the whole or any part of the loan without penalty on any day on which the credit union is open for business. On a first or second mortgage a credit union may require that any partial prepayment (1) be made on the date monthly installments are due and (2) be in the amount of that part of one or more monthly installments that would be applicable to principal.