Our Team


CPA, CCIFP, Principal

Small & Midsize Businesses
DEPARTMENT: Accounting

Clayton Stiffler, CPA, CCIFP, Principal

Clayton joined Maner Costerisan in 2014. His strong work ethic and passion for problem-solving helped him quickly move up the firm ranks. He was promoted to principal in 2024. Prior to joining Maner, Clayton worked at BS&A Software, gaining experience on their Financial Management support team.

At Maner, Clayton provides accounting and outsourced expertise to a variety of clients, including small and midsized businesses, with a specialization in supporting Maner’s cannabis and construction clients. He leads the firm’s Construction team and is one of less than 2,000 professionals nationwide to receive the Certified Construction Industry Financial Professional designation.

Clayton genuinely enjoys getting to know his clients and taking an active role in helping them grow their businesses. He credits his success at Maner to focusing first on the success of his clients. He lives by the mantra that their success leads to his.

Clayton graduated from Michigan State University with a Bachelor of Science in Accounting and a Master of Science in Accounting. While in college, he was on the Dean’s List for eight semesters. A traveler at heart, Clayton’s visited all the lower 48 states and hopes to visit the last two in the next few years.

A resident of East Lansing, Michigan, Clayton enjoys attending Michigan State athletic events with friends.

Every day at Maner is different than the one before. I thoroughly enjoy being "kept on my toes.”

Years of Experience



American Institute of Certified Public Accountants (AICPA)

Michigan Association of Certified Public Accountants (MICPA)

Construction Financial Managers Association – Lansing (CFMA)


Certified Public Accountant (CPA)

Certified Construction Industry Financial Professional (CCIFP)

QuickBooks Certified ProAdvisor