27 CFR §19.436

When a proprietor is required to pay tax on samples under § 19.434(f), the proprietor may include the tax on the next semimonthly or quarterly tax return, as appropriate, if qualified to defer payment of tax. If a proprietor is not qualified to defer payment of tax, the proprietor must prepay the tax on form TTB F 5000.24. See subpart I of this part for rules regarding the payment of taxes.