Pennsylvania businesses are required by law to pay taxes on any retail merchandise sold. In order to pay state sales taxes you need a Pennsylvania resale number -- also called a sales tax identification number. The Pennsylvania Department of Revenue issues all resale numbers to new and current businesses in Pennsylvania.

Step 1.

Navigate to the Pennsylvania Department of Revenue's website and locate the "Business Registration Forms" page. Locate the "PA-100" form on the page and download it to your computer. If you do not want to mail the form in, navigate to Pennsylvania's PA-100 site and begin the sales tax number registration process by clicking the "Register On-Line" button.

Step 2.

Fill out the PA-100 form. The form has 22 sections with details regarding each section at the end of the form. Provide your contact information, Social Security number, the name of your business and its address. Specify the structure of your business as well as any partners involved. Section 7 asks you to describe what percentage of your business is devoted to specific categories of operations. For example, if your business purely deals with selling retail items to customers, you would write "100 percent" next to the "Retail Trade" row of Section 7. Sign your name in the appropriate boxes of the form.

Step 3.

Obtain the signature of a notary in Pennsylvania. Form PA-100 requires the signature of a notary to verify that the information on the form is correct and valid. The maximum fee a notary can charge in Pennsylvania for signing your PA-100 is $5.

Step 4.

Submit your PA-100 form by mailing the form to the address listed or by clicking "Submit" on the PA-100 website. Processing for your resale number can take a few weeks. Your resale certificate is sent to you in the mail.