Quick Comparison
| Firm | Credentials | Focus |
|---|---|---|
| <a href="https://www.gierschgroup.com/">The Giersch Group</a> | Certified QuickBooks Online ProAdvisor firm founded in 2016 by Peter Giersch, with Milwaukee, Brookfield, and Madison offices and a family-business consulting heritage. | Virtual bookkeeping, outsourced accounting, payroll, QuickBooks training, CFO services, and consulting for small businesses, family businesses, franchises, and nonprofits. |
| <a href="https://www.diversifiedmgtsvc.com/">Diversified Management Services, Inc.</a> | Wauwatosa-based bookkeeping practice owned by Theresa Schwager that started in 1993 and has worked exclusively on QuickBooks Desktop and QuickBooks Online files since 2009. | Bookkeeping, accounting, payroll, QuickBooks training, business planning, and forensic accounting for small businesses across southeastern Wisconsin. |
| <a href="https://ambersbookkeeping.com/">Amber's Accounting & Bookkeeping</a> | Advanced Certified QuickBooks Online ProAdvisor practice founded in 2016 by Amber Kostelny, with a Milwaukee Street office and a US-based remote team. | Catch-up and clean-up bookkeeping, monthly bookkeeping, and monthly financial review and advisory work for service-based small businesses. |
1. The Giersch Group
- Address: 1661 N. Water St, Suite 408, Milwaukee, WI 53202
- Phone: (414) 255-4866
- Founder / Owner: Peter Giersch (Founder and President)
- Operating Since: 2016 (10 years)
- Credentials: Certified QuickBooks Online ProAdvisor firm; Peter Giersch holds a Certified Small Enterprise Advisor designation and Series 6 and 63 financial services certifications; named to the Milwaukee Business Journal 40 Under Forty list
- Service area: Milwaukee, Brookfield, Madison, and the wider southeastern Wisconsin region, plus virtual coverage nationwide
- Industries served: Family businesses, franchises, nonprofits, ecommerce, automotive, construction, restaurants, breweries and wineries, insurance agencies, architects, retail, startups, and publishers
- Website: gierschgroup.com
Downtown Milwaukee Headquarters
The Giersch Group runs from a 1661 N. Water Street suite in the East Town neighborhood of downtown Milwaukee, in the 53202 zip code. The firm has held that Water Street headquarters across the company’s own contact page, the Milwaukee Metropolitan Association of Commerce member directory, and the Clutch business profile, and it pairs the Milwaukee location with secondary offices in Brookfield and Madison. Peter Giersch is named as the Founder and President of the practice across the company’s own About page and his LinkedIn profile.
Family Business Consulting Heritage
Peter Giersch founded the shop in 2016 to carry forward the small-business consulting tradition he built at Cathedral Consulting Group, which he co-founded in 2004 in a basement north of Milwaukee. The Giersch Group positions itself as a family business helping other family-run businesses, small enterprises, franchises, and nonprofits, and the practice has grown to seven figures in revenue with hundreds of clients per the practice’s own history page. That family-business angle shows up in the published industry mix, which leans on closely held shops rather than rollup-style portfolio clients.
Certified QuickBooks Online ProAdvisor Stack
The firm holds Certified QuickBooks Online ProAdvisor status and offers a 50 percent QuickBooks Online discount to clients alongside the bookkeeping engagement. The team supports both QuickBooks Online files and QuickBooks Desktop files, and the published QuickBooks consulting page lists setup, training, troubleshooting, and ongoing optimization as stand-alone services. Owners can keep monthly books with the practice while also using the team for one-off QuickBooks cleanup or migration projects.
Full Stack Beyond Books
The published service mix runs past basic monthly bookkeeping to virtual CFO support, payroll, tax compliance, cash flow analysis, M&A consulting, family business succession planning, and grant writing for nonprofits. The firm serves more than 30 industries per its own site, including restaurants, breweries, architects, law firms, real estate, medical practices, churches, and salons. That breadth lets a closely held client keep books, payroll, advisory, and succession work with one practice rather than splitting them across separate vendors.
2. Diversified Management Services, Inc.
- Address: 10520 W Bluemound Rd, Suite 106, Wauwatosa, WI 53226
- Phone: (414) 231-3702
- Founder / Owner: Theresa Schwager (Owner and President)
- Operating Since: 1993 (33 years)
- Credentials: QuickBooks Desktop and QuickBooks Online specialist firm; Theresa Schwager holds an accounting background and works exclusively on QuickBooks files for client books since 2009
- Service area: Wauwatosa headquarters serving Milwaukee, Waukesha, Ozaukee, and the wider southeastern Wisconsin region
- Industries served: Real estate, small service businesses, retail, professional services, and other small businesses across southeastern Wisconsin
- Website: diversifiedmgtsvc.com
Wauwatosa Bluemound Road Office
Diversified Management Services works from a 10520 W Bluemound Road office in Suite 106 in Wauwatosa, the Milwaukee County suburb west of downtown Milwaukee, in the 53226 zip code. The firm has held that Bluemound Road address across the company’s own contact page, the Yelp business listing, the Yellow Pages directory entry, and a Manta business profile. Theresa Schwager is named as the Owner across the firm’s own About page and an external accountant database listing.
Three Decade Founder Track Record
Theresa Schwager started DMS on October 1, 1993 as a part-time sole proprietorship, moved it to a full-time sole proprietorship on January 1, 1999, and incorporated the practice on October 1, 2003 per the company’s own About page. The firm celebrated 25 years in business in 2018 and now sits 33 years past the 1993 founding date, well past the five-year minimum bar this directory applies. That long window under one named owner is rare in the bookkeeping market and signals a stable, locally rooted practice.
QuickBooks Exclusive Bookkeeping Workflow
DMS works exclusively on QuickBooks Desktop and QuickBooks Online files for client books since 2009 per the shop’s own QuickBooks page. The team also delivers QuickBooks training as a stand-alone service for owners who want to keep books in-house, and the practice handles QuickBooks cleanup engagements when files arrive in poor shape. That QuickBooks-only workflow keeps the practice deep on one platform rather than spread thin across competing accounting tools.
Small Business Service Mix
The published service mix covers bookkeeping, accounting, payroll, QuickBooks training, business planning and development, and forensic accounting. The firm leans on small businesses in southeastern Wisconsin, including a published real estate bookkeeping vertical for landlords and property managers. That mix lets a small-business owner keep books, payroll, and quarterly planning work with one Wauwatosa practice rather than running parallel vendor contracts for each piece.
3. Amber’s Accounting & Bookkeeping
- Address: 790 N Milwaukee Street, Suite 300, Milwaukee, WI 53202
- Phone: (708) 925-7574
- Founder / Owner: Amber Kostelny (Owner and CEO)
- Operating Since: 2016 (10 years)
- Credentials: Advanced Certified QuickBooks Online ProAdvisor; team members are QuickBooks ProAdvisors with higher-level degrees in business and accounting; US-based bookkeeping team with no overseas outsourcing
- Service area: Milwaukee Street office in downtown Milwaukee serving clients across Wisconsin and nationwide via virtual delivery
- Industries served: Service-based businesses, breweries, engineers, financial advisors, and gyms (no nonprofits or retail per firm policy)
- Website: ambersbookkeeping.com
Milwaukee Street Downtown Office
Amber’s Accounting & Bookkeeping holds a 790 N Milwaukee Street office in Suite 300 in downtown Milwaukee, in the 53202 zip code. The firm has listed that Milwaukee Street address across its own Milwaukee bookkeeping page and external business directories, and it pairs the Milwaukee location with a remote team that supports clients across multiple states. Amber Kostelny is named as the Owner and CEO of the practice across the practice’s own site, her LinkedIn profile, and the Intuit Find-a-ProAdvisor directory.
Founder QuickBooks Pedigree
Amber Kostelny earned her QuickBooks Online ProAdvisor credential in 2016 and launched Amber’s Bookkeeping the same year per her LinkedIn profile and the firm’s own about content. Her work with QuickBooks goes back to 2002, when friends and family asked for help organizing finances. The firm reports support for 242 clients and reconciliation of more than 1,017 bank accounts since launch, and the team holds Advanced Certified ProAdvisor status alongside the standard Online ProAdvisor credential.
Service Business Specialization
The firm focuses on service-based businesses, breweries, engineers, financial advisors, and gyms per the company’s own homepage and Milwaukee bookkeeping page, and explicitly excludes nonprofits and retail clients. That tight industry mix lets the team build deep workflow templates for service businesses rather than chase every small-business niche. Minimum monthly engagements start at $500 per the shop’s own pricing notes, which positions the practice above entry-level bookkeeping shops without entering CPA-firm pricing tiers.
Three Service Tracks
The published service catalog runs three tracks: catch-up and clean-up bookkeeping for owners with backlog, monthly bookkeeping for ongoing engagements, and a monthly financial review and advisory track for owners who want active financial guidance alongside the books. The team works exclusively on QuickBooks Online and uses a US-based bookkeeper roster without overseas outsourcing. That setup fits owners who want a steady monthly close plus periodic advisory check-ins on the same QuickBooks Online file.
Reference Notes
The Giersch Group address (1661 N. Water St, Suite 408, Milwaukee, WI 53202) and phone (414) 255-4866 cross-checked across the practice’s own contact page, the Milwaukee Metropolitan Association of Commerce business directory, a Clutch company profile, and a Facebook business page. The 2016 founding year and Peter Giersch as Founder and President sourced from the firm’s own About and Peter Giersch biography pages and confirmed against the company’s history page describing the transition from Cathedral Consulting Group. Certified QuickBooks Online ProAdvisor status sourced from the shop’s QuickBooks Consulting page and supported by ProAdvisor banner mentions across firm service pages.
Diversified Management Services address (10520 W Bluemound Rd, Suite 106, Wauwatosa, WI 53226) and phone (414) 231-3702 confirmed across the practice’s own About page, the Yelp business listing, the Yellow Pages Wauwatosa directory entry, a Manta business profile, and a ZoomInfo company record. The 1993 founding date and the staged 1999 sole-proprietorship and 2003 incorporation milestones sourced from the firm’s own About DMS page, alongside the 2018 25-year anniversary blog post on the company’s site. Theresa Schwager as Owner sourced from her LinkedIn profile and the shop’s own pages, and the QuickBooks-exclusive bookkeeping workflow since 2009 sourced from the practice’s QuickBooks page.
Amber’s Accounting & Bookkeeping address (790 N Milwaukee Street, Suite 300, Milwaukee, WI 53202) and phone (708) 925-7574 cross-checked across the firm’s own Milwaukee bookkeeping page, the Intuit Find-a-ProAdvisor directory entry for Amber Kostelny, and the company’s Facebook business page. The 2016 founding year and Amber Kostelny as Owner and CEO sourced from her LinkedIn profile and confirmed against the shop’s homepage and Intuit ProAdvisor profile. Advanced Certified QuickBooks Online ProAdvisor status sourced from the practice’s homepage and the firm’s secondary site at ambersbookkeepingllc.com.
All three firms appear as independent, founder-led, or family-led practices and not as franchised or rolled-up brands such as Bench, Pilot, QuickBooks Live, BELAY, Bookkeeper360, Bookminders, Supporting Strategies, Bookkeeper.com, or 1-800Accountant.
Selection Methodology
This list applies four filters to the Milwaukee market. First, the company has to be independent, family owned, or founder led rather than part of a national rollup or franchise brand. Second, the shop must show active QuickBooks credentials or a QuickBooks-centered practice, with that focus visible on its own site or on a third-party directory. Third, the practice has to have been in business for at least five years, with priority given to firms past the ten-year mark. Fourth, the firm has to position itself as a bookkeeping practice rather than a pure CPA tax-prep shop. Public address and phone data also had to match across at least two independent sources, including the company’s own site plus a Better Business Bureau record, a Yelp business profile, a Chamber of Commerce listing, or another third-party directory. National rollup brands such as Bench, Pilot, QuickBooks Live, BELAY, Bookkeeper360, Bookminders, Supporting Strategies, Bookkeeper.com, and 1-800Accountant were excluded by design, since this directory targets locally owned shops in the Milwaukee market.
Frequently Asked Questions
Do these firms serve clients outside Milwaukee proper?
Yes. The Giersch Group runs from a Water Street headquarters in downtown Milwaukee and pairs that office with secondary locations in Brookfield and Madison, so the practice covers small businesses across southeastern Wisconsin and into the Madison metro, plus virtual coverage nationwide. Diversified Management Services works from a Bluemound Road office in Wauwatosa and serves small businesses across Milwaukee, Waukesha, Ozaukee, and the wider southeastern Wisconsin region. Amber’s Accounting & Bookkeeping holds a Milwaukee Street office in downtown Milwaukee and supports a US-wide client base through a remote QuickBooks Online workflow.
Are these firms CPA practices or bookkeeping practices?
All three position themselves as QuickBooks-centered bookkeeping practices rather than as CPA audit firms. The Giersch Group runs as a Certified QuickBooks Online ProAdvisor firm with bookkeeping, payroll, virtual CFO, and consulting services for family businesses and nonprofits, and offers tax compliance support alongside the books. Diversified Management Services runs as a QuickBooks-exclusive bookkeeping shop with payroll, business planning, and forensic accounting services across southeastern Wisconsin. Amber’s Accounting & Bookkeeping runs as an Advanced Certified QuickBooks Online ProAdvisor practice with three service tracks for service-based businesses. Owners who need formal CPA audit or attest work would still need to retain a licensed CPA firm separately.
Do Milwaukee bookkeeping firms typically offer remote service?
Yes. The Giersch Group explicitly offers 100 percent virtual bookkeeping services to clients across the country alongside its physical offices in Milwaukee, Brookfield, and Madison, with a remote bookkeeper, controller, and CFO team. Amber’s Accounting & Bookkeeping works exclusively on QuickBooks Online files with a US-based remote team, which lets the shop support clients across Wisconsin, Illinois, Colorado, and other states from the Milwaukee Street office. Diversified Management Services keeps a stronger southeastern Wisconsin focus from its Wauwatosa headquarters but supports remote QuickBooks Online engagements alongside on-site work.
How long have these firms been operating?
Diversified Management Services was founded in 1993 (33 years). The Giersch Group was founded in 2016 (10 years). Amber’s Accounting & Bookkeeping was founded in 2016 (10 years). Each firm sits well past the five-year minimum tenure threshold this directory applies, and each has stayed independent across its full window under named founder or owner control.
Editorial Note
This post was prepared on 2026-05-11 using publicly available web sources, including each firm’s own website, third-party business directories such as Yelp, the Milwaukee Metropolitan Association of Commerce member directory, the Yellow Pages, Manta, Clutch, ZoomInfo, the Intuit Find-a-ProAdvisor directory, and LinkedIn business profiles. Address, phone, ownership, tenure, and credential details reflect those sources at the time of writing. Readers should confirm current details directly with each firm before contracting, since office locations, phone numbers, and ownership can change after publication.