Okla. Stat. tit. 68, § 68-2912: Taxes on real estate as lien

As between grantor and grantee of any land where there is no

express agreement as to who shall pay the taxes that may be assessed

thereon, taxes on any real estate shall become a lien on such real

estate on October 1 of each year, and if such real estate is

conveyed after said date the grantor shall pay such taxes, and if

conveyed on or prior to October 1st of such year the grantee shall

pay such taxes.