Okla. Stat. tit. 68, § 68-221.1: Date of postmark deemed to be date of delivery or of

payment.

A. For any return, claim, statement, or other document required

to be filed or any payment required to be made within a prescribed

period or on or before a prescribed date under authority of any

provision of a tax law of this state, the date of the postmark

stamped on the cover in which the return, claim, statement, or other

document or payment is mailed shall be deemed to be the date of

delivery or the date of payment, as the case may be.

B. The provisions of this section shall apply only if:

1. The postmark date falls within the prescribed period or on

or before the prescribed date for filing, including any extension,

of the return, claim, statement, or other document or for making

payment, including any extension granted for making such payment;

and

2. The return, claim, statement, or other document or payment

was, within the prescribed period or on or before the prescribed

date for filing, deposited in the mail in the United States in an

envelope or other appropriate wrapper, postage prepaid, properly

addressed to the Oklahoma Tax Commission, agency, officer, or office

with which the return, claim, statement, or other document is

required to be filed, or to which the payment is required to be

made.

C. The provisions of this section shall apply in the case of

postmarks not made by the United States Postal Service only and to

the extent provided by rules or regulations prescribed by the Tax

Commission.

D. For purposes of this section, if any return, claim,

statement, or other document or payment, is sent by United States

registered mail, the registration shall be prima facie evidence that

the return, claim, statement, or other document was delivered to the

Tax Commission, agency, officer, or office to which addressed, and

the date of registration shall be deemed the postmark date. The Tax

Commission is authorized to provide by rules or regulations the

extent to which the foregoing provisions of this subsection with

respect to prima facie evidence of delivery and the postmark date

shall apply to certified mail.

E. The provisions of this section shall not apply with respect

to the filing of a document in, or the making of payment to, any

court, or to currency or other medium of payment unless actually

received and accounted for, or returns, claims, statements or other

documents or payments which are required under any provision of a

tax law or rules of this state to be delivered by any method other

than by mailing.

F. Any reference in this section to the United States mail

shall be treated as including a reference to any designated delivery

service, and any reference in this section to a postmark by the

United States Postal Service shall be treated as including a

reference to any date recorded or marked as described in this

subsection by a designated delivery service. For purposes of this

section, the term “designated delivery service” means a delivery

service provided by a trade or business if the service is designated

by a rule of the Tax Commission for purposes of this section. The

Tax Commission may designate a delivery service under the preceding

sentence only if the Tax Commission determines that the service is

available to the general public, is at least as timely and reliable

on a regular basis as the United States mail, records electronically

to its data base kept in the regular course of its business or marks

on the cover in which any item referred to in this section is to be

delivered, the date on which the item was given to the service for

delivery, and meets all other criteria prescribed by the Tax

Commission. The Tax Commission may provide a rule similar to the

rule stated in the first sentence of this subsection with respect to

any service provided by a designated delivery service which is

substantially equivalent to United States registered or certified

mail.