Accounts Payable Specialist at S3 AeroDefense LLC – Milwaukee, Wisconsin

Purpose of the Job

The Accounts Payable (AP) Specialist supports the daily operations of the Accounting and Finance department by accurately processing accounts payable transactions, maintaining vendor relationships, and ensuring timely, compliant payments while supporting financial reporting activities.

Reports to: Director of Finance

Key Duties and Responsibilities

Invoice Processing & Payments

• Perform three-way match of vendor invoices to purchase orders and receiving documentation.
• Accurately enter invoices into the ERP system and resolve discrepancies in coordination with purchasing, warehouse, logistics, quality, and compliance teams.
• Prepare weekly payment runs, review AP aging, and set up check, ACH, and wire payments for Director of Finance approval.
• Record recurring electronic payments and ensure timely submission through banking portals.
• Process employee credit card transactions and record related general ledger entries.
• Monitor open payables and ensure timely payment in accordance with vendor terms and cash management objectives.

Vendor Management & Compliance

• Maintain vendor master records, including vendor setup, updates, and credit applications.
• Independently verify vendor banking changes and adhere to internal fraud prevention procedures.
• Collect and maintain vendor W-9 forms and support annual 1099 preparation.
• Review invoices for proper sales and use tax treatment and coordinate use tax accruals when necessary.

Reconciliation & Operational Support

• Prepare monthly AP subledger reconciliations.
• Support month-end, quarter-end, and year-end close activities related to accounts payable.
• Assist with internal and external audit requests by providing supporting documentation.
• Collaborate with cross-functional teams to resolve lagging receivers, freight approvals, claims, and other invoice discrepancies.

Controls & Policy Adherence

• Follow established internal controls, segregation of duties, and payment authorization protocols.
• Maintain organized documentation and audit-ready records.
• Comply with all company

• Bachelor’s degree in Accounting or Finance.
• Minimum of 3 years of experience in an accounts payable role.
• Working knowledge of U.S. GAAP as it relates to accounts payable.
• Experience with ERP accounting systems.
• Proficiency in Microsoft Excel and other Microsoft Office applications.
• Strong organizational skills with high attention to detail.
• Ability to manage deadlines in a fast-paced environment.
• Effective communication skills and ability to work cross-functionally with internal teams and vendors.
• High level of integrity and commitment to internal controls and fraud prevention.