Tax Manager

About Mainspring

Mainspring Energy manufactures and delivers fuel-flexible, low-emissions local power solutions that rapidly add new capacity and deliver reliable, affordable, and sustainable electric power. The company began commercial shipments of its Mainspring Linear Generators in 2020 and today has hundreds of megawatts in advanced development and field operations for leading Fortune 500 companies, data centers, and utilities. Mainspring also partners with global energy leaders including AEP, NextEra Energy Resources, Schneider Electric, and more.

The core values that ground our work, guide our decisions, and connect us together:

Pragmatic Optimism

Excellence without Ego

Proactive Collaboration

As Mainspring continues to scale, we are looking for a Tax Manager who wants to move beyond processing returns and become a true business operator. Reporting to the VP of Finance & Corporate Controller, you will build and own key tax and risk management processes that support the company’s next stage of growth.

Rather than stepping into a mature tax department, you will have the opportunity to help build one. This role offers meaningful ownership, broad exposure across the business, and direct visibility with senior leadership. You will influence how Mainspring approaches tax compliance, risk management, automation, and scalability while developing the skills needed to grow into future management and leadership opportunities.

This role is ideal for a technically strong tax professional who enjoys creating structure, improving processes, and taking ownership. You will partner across Finance, Legal, Operations, Sales, and FP&A while serving as Mainspring’s internal resource on tax compliance, tax reporting, and corporate insurance matters.

If you are a builder who enjoys combining technical expertise with operational impact, this is an opportunity to make a lasting mark on a rapidly growing clean energy company.

Key Responsibilities:

Tax Compliance & Reporting

Own federal and state income tax compliance activities and coordinate with external tax advisors

Manage quarterly and annual ASC 740 tax provision processes

Maintain tax calendars, filing schedules, and payment obligations across jurisdictions

Support audits, tax notices, and inquiries from federal and state authorities

Monitor tax law changes and assess business impacts

Sales, Use & Property Tax

Lead multi-state sales and use tax compliance, including nexus analysis and registrations

Manage sales tax audits, exemptions, and documentation requirements

Oversee business personal property tax filings and related compliance activities

Partner with internal stakeholders to ensure accurate tax treatment of transactions and assets

Risk Management & Insurance

Help manage Mainspring’s corporate insurance programs, including renewals, broker relationships, and coverage reviews

Support contract insurance reviews and claims management activities

Partner with Legal and Operations to identify and mitigate emerging business risks

Process Improvement & Scale

Build and document scalable tax processes and controls

Evaluate and implement tax automation tools where appropriate

Bring tax activities in-house where it creates efficiency and better business visibility

Help establish the foundation for a larger, more sophisticated tax and risk management function

Required Qualifications

5+ years of progressive tax experience in public accounting, industry, or a combination of both

Strong knowledge of ASC 740 income tax accounting and tax provision processes

Experience with federal and state income tax compliance

Hands-on experience with multi-state sales and use tax compliance and nexus analysis

Familiarity with property tax compliance in multiple jurisdictions

Ability to manage multiple deadlines and priorities independently

Strong communication skills and ability to work effectively with non-tax stakeholders

Preferred Qualifications

Big 4 or regional public accounting experience

Experience supporting manufacturing, industrial, energy, hardware, or capital equipment businesses

Exposure to energy tax incentives, R&D tax credits, or other business tax credits

Experience with tax technology platforms such as Avalara, Vertex, OneSource, or CorpTax

Exposure to IPO readiness, public company reporting, or SOX environments

Familiarity with corporate insurance programs and risk management activities