Who is obliged to register sales tax:
If a remote seller is not already registered in Oklahoma then he/she must file an election with the Oklahoma Tax Commission to either collect and remit the sales tax or to comply with statutory notice and reporting requirements (a small seller is an exception).
Merchant thresholds by state
You do not need to register and collect Oklahoma sales/use tax if two conditions are met:
1) you only make taxable sales into Oklahoma through a marketplace and
2) the marketplace facilitator or referrer is collecting and remitting Oklahoma sales/use tax on your behalf, then.
To register for an Oklahoma tax permit, you can visit the website at tax.ok.gov.
Sales tax payment and filing date:
Most of the remote sellers must fill and submit tax returns before the 20th day of the month following the month in which the sale was made.
A seller whose tax liability does not exceed $ 50 per month can file semi-annual tax returns. Semi-annual sales tax reports are due by July 20th (for the period from January to June) and January 20th (for the period from July to December).
Penalty and interest:
Fail to pay delinquent taxes:
$15 or an amount equal to 10%, but not to exceed $200, of the total amount of tax, penalty, and interest or the actual liability at the date of issuance of the warrant.
The penalty for late filing of the tax return within 15 days after the tax payment is 10% of the total tax amount.
Official fines bulletin:https://www.ok.gov/tax/documents/AVVN.pdf