Subsidized housing applications specifically require certain types of documents, and many market-rate apartments may have similar requirements depending on the landlord or management company. List of things you need

Photo ID (WI ID and duplicate DL can be requested here:https://wisconsindot.gov/Pages/online-srvcs/DLID-Services.aspx)
Social Security cards (Replacement SS card may be ordered here: https://www.ssa.gov/number-card/replace-card)
Birth certificates (Children under 18)
- For children born in WI copies of their birth certificates may be obtained online here: https://www.vitalchek.com/wistorefront/customer/wi/wiHome.xhtml?click_id=592505259768217602&ppc=0
- Or in person at your Register of Deeds office
Current Social Security benefit letter (if applicable) (https://www.ssa.gov/manage-benefits/get-benefit-letter)
Two months of pay stubs (if applicable)
Current bank statement (Contact your bank or download from your online banking app)
Verification of investments (if applicable)
Food Share verification letter (if applicable) (Contact the Southern Consortium 888-794-5780 or go through your account on ACCESS)
Child support verification letter (if applicable) (Contact the county that the order was given in https://dcf.wisconsin.gov/cs/agencylist)

Resources:

Tips to Filling Out a Rental Application

What to say to a landlord: A phone call script

To help you create a strong housing application, check out these example letters to explain common situations. These templates can be customized to help you communicate effectively with property managers about credit history issues, gaps in housing history, or other circumstances that may require clarification. While these examples can serve as a guide, be sure to personalize them to reflect your specific situation.