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

$116,000 - $175,000 a year

This position is onsite at our Menlo Park HQ. The salary will be adjusted to reflect local market conditions based on employee location as well as the experience of the employee. Along with the base salary, Mainspring offers stock options + benefits.

Does your experience not meet all of our posted requirements? Studies have shown that some people are less likely to apply to positions unless they meet every listed requirement. At Mainspring, we are committed to building a diverse, inclusive, flexible, and collaborative environment, so if you want to help us transition the world to clean and affordable electricity, and don't meet all posted requirements for a particular role, we'd still love to hear from you. Mainspring can sometimes be flexible enough to shift responsibilities for the right person, or otherwise identify open or upcoming roles that may better fit your professional background.