Accounts Payable Manager

About this role

ABOUT MARIANA MINERALS

Mariana Minerals is a software-first, vertically integrated minerals company on a mission to supply the critical minerals powering modern energy, AI, and defense technologies. We’re reimagining the minerals supply chain by combining deep industry expertise with advanced software, automation, and data-driven decision-making.

THE ROLE

We are seeking an experienced Accounts Payable Manager to lead Mariana Minerals’ accounts payable operations and help build a scalable, technology-enabled procure-to-pay function. This position is responsible for ensuring the timely and accurate processing of supplier invoices, compliance with company purchasing policies and internal controls, and leading a high-performing AP team.

The ideal candidate combines strong operational accounting experience with a continuous-improvement mindset and enjoys building efficient processes that leverage automation. As Mariana continues to grow, this role will play a key part in implementing best-in-class procure-to-pay practices, improving vendor relationships, strengthening internal controls, and supporting the company’s readiness for continued growth.

This role will work closely with Procurement, Operations, Accounting, Treasury, FP&A, and business leaders across multiple operating locations.

WHAT YOU’LL DO

ACCOUNTS PAYABLE OPERATIONS

- Supervise and assist in the daily processing of vendor invoices across multiple legal entities.

- Ensure invoices are processed accurately, completely, and in accordance with company policies and payment terms.

- Ensure three-way matching of purchase orders, goods receipts, and vendor invoices.

- Review invoice coding for accuracy, including general ledger accounts, departments, projects, entities, and budget classes.

- Manage invoice queues and ensure service-level expectations for invoice processing are achieved.

- Coordinate weekly payment proposals with Treasury while supporting working-capital objectives and vendor relationships.

- Monitor accounts payable aging and proactively

VENDOR MANAGEMENT

- Serve as the primary escalation point for vendor inquiries, account statements, and payment disputes.

- Build strong relationships with key suppliers while ensuring consistent communication regarding payment status.

- Coordinate the resolution of invoice discrepancies with Procurement and operational teams.

- Oversee vendor onboarding documentation, including W-9 or W-8 forms, banking information, tax forms, certificates of insurance, and other required support.

- Prepare and complete vendor credit applications to establish or expand supplier credit terms.

- Assist in maintaining an accurate vendor master and support vendor due-diligence processes.

INVOICE APPROVALS AND EXCEPTION MANAGEMENT

- Supervise, coach, mentor, and develop Accounts Payable staff.

- Establish performance expectations and monitor individual and team productivity, quality, and timeliness.

- Conduct regular performance reviews and provide ongoing feedback and coaching.

- Develop cross-training plans to ensure operational continuity and appropriate coverage.

- Promote a culture of customer service, accountability, collaboration, and continuous improvement.

TEAM LEADERSHIP

- Supervise, coach, mentor, and develop Accounts Payable staff.

- Establish performance expectations and monitor individual and team productivity, quality, and timeliness.

- Conduct regular performance reviews and provide ongoing feedback and coaching.

- Develop cross-training plans to ensure operational continuity and appropriate coverage.

- Promote a culture of customer service, accountability, collaboration

PROCESS IMPROVEMENT AND INTERNAL CONTROLS

- Identify opportunities to automate invoice processing, approval workflows, and exception handling.

- Support the implementation and optimization of AP automation tools, OCR technologies, and ERP workflows.

- Develop and maintain standard operating procedures, desk procedures, and process documentation.

- Ensure compliance with internal controls, segregation of duties, procurement policies, and payment authorization requirements.

- Support internal and external audit requests and remediation activities.

- Monitor key performance indicators and recommend

REPORTING AND ANALYTICS

- Prepare and report key Accounts Payable metrics, including:

- Invoice processing cycle time and backlog

- Percentage of invoices supported by purchase orders

- Outstanding approval aging

- Vendor aging

- Non-PO invoice volume

- Provide regular reporting and recommendations to Finance leadership to improve operational efficiency and support decision-making.

DESIRED QUALIFICATIONS

- Bachelor’s or Associate’s degree in Accounting, Finance, Business Administration, or a related field

- Five or more years of progressive Accounts Payable experience, including at least two years supervising or leading AP staff

- Experience in manufacturing, mining, energy, industrial, construction, or another asset-intensive industry is preferred

- Strong understanding of procure-to-pay processes, invoice matching, vendor management, and payment controls

- Experience with ERP systems such as Odoo, NetSuite is preferred

- Experience with AP automation platforms and OCR technologies is highly desirable

- Strong knowledge of internal controls, segregation of duties, and financial compliance

- Experience implementing process improvements and automation initiatives

- Excellent organizational skills and the ability to manage competing priorities in a fast-paced environment

- Strong analytical, problem-solving, interpersonal, and communication skills

OUR CULTURE IS BUILT ON THREE PRINCIPLES:

Extreme Ownership – We take full responsibility for outcomes, relentlessly driving toward solutions.

Engineer Out Requirements, then Automate – We simplify, optimize, and then automate for scale.

Share Your Legos – We collaborate op

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