Serving Pocahontas for over 50 years

Aerial view of a small town with buildings, roads, green fields, and a prominent water tower with red and white stripes.

Who We Are

The history of the firm dates back to 1972, when Ron Osweiler began working out of the basement of the Burns-Fitzgerald building (232 N Main). He later relocated to what is now Sinek Vision Clinic (230 N Main). Jeff Johnson started working full-time for Ron in 1979, and Jeff purchased the practice in 1982 after Ron’s passing. In 1989, Jeff moved to the current location of the business, 223 N Main. Nick Wiemers began working for the firm in 2019 and Andrew Klaassen joined in 2022. Jeff sold his practice on November 1, 2025, which launched AgriTax Advisors, PLLC.

  • Young man with short brown hair and a big smile, wearing a dark navy shirt with small white polka dots, standing against a plain light-colored background.

    Nick Wiemers, EA

    Manager & Tax Advisor

    Nick began working with Jeff Johnson in 2019 and provides advisory and tax services to individuals and small businesses. He graduated Summa Cum Laude in 2018 with a Finance degree from the University of Northern Iowa. Nick particularly enjoys working with clients in the agriculture and transportation industries to create long-term tax and financial strategies. Outside of the office, Nick enjoys farming with his father, serving on local boards, and traveling with his wife.

  • A young man with short brown hair, glasses, and a blue shirt smiling at the camera, sitting in front of a computer monitor with a blue background.

    Andrew Klaassen, CPA

    Manager & Tax Advisor

    Andrew began working with the firm in 2022 and provides advisory, tax, and accounting services for individuals and small businesses. He graduated in 2021 from Buena Vista University with degrees in Accounting, Ag Business, and Business. Andrew has a small farming operation of his own and especially enjoys growing relationships with agricultural clients, while developing tax and financial strategies. Outside of work, he enjoys spending time with his wife and being active.

  • A smiling middle-aged man with glasses and gray hair, wearing a light blue shirt, sitting at a desk in an office with framed documents and a photo on the wall behind him.

    Jeff Johnson, EA, LPA, CFP

    Tax Advisor

    Jeff established Jeffrey A Johnson, LPA PC in 1982 after graduating with an Associate of Specialized Business with an Accounting major in May of 1979. He sold his practice in 2025, but continues to serve clients. With over 45 years of experience, Jeff specializes in tax preparation and bookkeeping for farmers and small businesses. Jeff and his wife Kathy have been married for 46 years and have three grown children and six grandchildren. Outside of work, he enjoys golfing, biking, and serving local community organizations.

  • A woman with shoulder-length brown hair smiling, wearing a navy blue collared shirt with a logo that says Jeffrey A. Johnson Accounting, standing in front of wooden paneling.

    Mary Saathoff

    Payroll Administrator

    Mary has been with the firm since 2015 performing payroll and administrative duties. She has an Accounting degree from Iowa Central Community College and spent eight years as a Personnel Management Specialist for the US Army Reserves. Mary has a large family including a grown daughter. She enjoys walking, road trips, and reading; having read over 3,000 books that are currently in her electronic library!

  • Kathy Josephson

    Bookkeeper

    Kathy has been working with the firm since 2013 and handles bookkeeping and administrative services. She has degrees in Accounting and Sales & Marketing alongside over 25 years of experience in the accounting field. Kathy and her husband live on and farm the 100+ year old Josephson family farm. She is a proud mom of three, grandma of four and in her spare time enjoys reading, sewing and spending time with the kids, kids-in-law and grandkids.