Okla. Stat. tit. 68, § 68-2208: Refusal of railroad to comply with act, liability -

Taxpayer estopped to question Commission's determination, when.

If any railroad company shall fail or refuse to make any report

required by this act, or shall fail or refuse to withhold and pay

the tax due from any such company within the time hereinbefore

provided, it shall be liable for the full amount of such tax,

penalty and costs of collection.

If any freight line company, equipment company or mercantile

company as hereinbefore defined, shall refuse or neglect to make any

reports required by this act, or shall refuse or neglect to permit

an examination of its books, records, accounts and papers upon

demand of the Tax Commission, or shall refuse or neglect to appear

before the said Commission in obedience to its citation or summons;

it shall be estopped to question or impeach the action or

determination of the said Commission or the validity of the tax

imposed hereunder.