Okla. Stat. tit. 62, § 62-357: Rate of interest on funding or refunding bonds - Period

elapsing before refund.

Funding or refunding bonds of a county, city, town, township,

board of education or school district issued under existing laws may

not bear a greater rate of interest than the indebtedness which is

funded or refunded, or may bear such rate or rates of interest which

shall not constitute a greater overall interest cost existing on

indebtedness which is funded or refunded. Provided that no bonded

and/or interest coupon indebtedness shall be refunded except such as

have been issued and outstanding at least one (1) year at the time

of such refunding.