Collin Products received notice of a $27,600 income tax deficiency plus $3,900 interest. The deficiency related to an incorrect method of accounting for business inventory. Compute the after-tax cost of the $3,900 interest payment assuming that:

a. Collin Products is a corporate taxpayer with a 35 percent marginal tax rate.

Collin Products is a sole proprietorship owned by Leslie Collin. Leslies marginal tax rate on her Form 1040 is 39.6 percent.