KY-OH bilateral state-wage reciprocity layered against Cincinnati municipal income-tax non-reciprocity — a Campbell-resident CPA or EA boutique runs procedural-compliance work for 15,000-25,000 Cincinnati-commuter Campbell-resident households on complexity-adjusted fees, not rate-arbitrage.

Layer 1 is state-level wage reciprocity. Kentucky and Ohio maintain a bilateral arrangement under Kentucky Department of Revenue guidance and Ohio Revised Code section 5747.05. A Campbell resident with Ohio-source wages files Kentucky Form 740, reports the Ohio-source wages, and pays Kentucky individual income tax. The earner files Ohio Form IT-2023 at the W-4 stage to direct the Ohio employer not to withhold Ohio state income tax. If Ohio withholding was nonetheless taken, the earner files Ohio IT-1040 with the reciprocity schedule to recover it. The converse runs for Ohio residents with Kentucky-source wages.

Layer 2 is the Cincinnati municipal income tax. Cincinnati levies a municipal earnings tax on wages earned within city limits. The current rate cited here is 1.8 percent, pending confirmation against the Cincinnati Income Tax Division. State reciprocity does not exempt the Cincinnati municipal tax — municipal-level non-reciprocity is the real complication. Kentucky Form 740 provides a credit against Kentucky state liability for city or occupational taxes paid to non-Kentucky jurisdictions, with the cap and mechanic governed by the current Pub 740 instructions.

Layer 3 is the post-COVID remote-work sourcing change. Cincinnati's municipal sourcing for remote workers shifted after the 2020 to 2022 emergency-sourcing window under Ohio Revised Code section 29 expired. Current Cincinnati Income Tax Division guidance on day counting, principal-place-of-work designation, and refund-claim mechanics for days worked outside city limits is the active complexity. A Campbell-resident hybrid worker — three days in the Cincinnati office, two days in a Fort Thomas home office — owes municipal tax on a fraction of total wages and is entitled to a refund on the home-office days. That refund claim is the recurring per-return product.

Layer 4 is small-employer multi-state payroll. A Campbell-resident operator running a residential-trades LLC, a lawn-care book, or an insurance agency who hires a Cincinnati-resident employee — or a Cincinnati-resident operator hiring a Campbell-resident employee — has to set up multi-state payroll registration. That spans Kentucky Department of Revenue and Ohio Department of Taxation employer withholding accounts, Cincinnati Income Tax Division employer registration, and Kentucky and Ohio unemployment-insurance accounts. The reciprocity election at the employee's W-4 stage runs through Kentucky Form 42A809 (Campbell employer with a Cincinnati-resident employee) or Ohio Form IT-4 (the converse).

Layer 5 is estate planning and retirement-account state sourcing. Campbell-resident retirees drawing pension, deferred-compensation, or IRA distributions tied to prior Cincinnati employment hit source-state determination issues for the retirement-income portion. Federal P.L. 104-95 (the source-state-of-residence rule for pensions) intersects with deferred-compensation rules under IRC sections 3121(v)(2) and 457. Estate planning for cross-state decedents — a Campbell resident with Ohio-situs real property or an Ohio-source trust corpus — requires dual-state probate or ancillary-administration coordination.

Demand sizing. Working estimate: 30 to 50 percent of Campbell's roughly 45,000 to 50,000 employed working-age population works in Cincinnati or surrounding Hamilton County, Ohio. That gives a band of 15,000 to 25,000 Campbell-resident Cincinnati commuters, pending verification against the most recent LEHD LODES vintage. Of those, the working assumption is that 60 to 75 percent commute into the Cincinnati municipal limits. A 0.5 to 1.5 percent catchment share supports an annual book of 75 to 375 returns. At complexity-adjusted fees of $400 to $1,500 per return (single-W-2 reciprocity-only at the low end; multi-state plus hybrid-worker refund plus Schedule C plus Cincinnati-municipal refund at the high end), the individual-return book alone generates $30K to $560K.

Founder model. A solo Kentucky-licensed CPA with Ohio reciprocal license or practice privilege under Uniform Accountancy Act section 23, or a solo Enrolled Agent (federal-only credential; works across both states without state-board licensure for tax-return preparation), serving four lanes: Cincinnati-commuter individual tax prep, small-employer multi-state payroll setup and recurring filing, hybrid-worker refund claims and audit defense, and estate-planning plus retirement-income state-sourcing advisory. A JD-CPA founder extends the estate-planning lane; an EA-only founder stays in the prep plus payroll-compliance lane and refers estate work to an outside attorney while keeping the tax-sourcing advisory portion.

Engagement-fee structure (complexity-adjusted, founder-billable): individual tax return single-W-2 Cincinnati-commuter Campbell-resident with reciprocity and Cincinnati municipal-tax filing $400-$700 per return; multi-W-2 household plus hybrid-worker refund claim plus Schedule-C side-business plus multi-state K-1 from partnership interest $800-$1,500 per return; small-employer multi-state payroll setup $1,500-$5,000 per employer; small-employer multi-state payroll recurring $200-$600 per month; estate-planning plus retirement-account state-sourcing engagement $2,500-$15,000 per engagement; hybrid-worker Cincinnati-municipal-refund flat fee $250-$500 per claim.

Year 1 founder-only book-build: 80-120 individual returns at $500 average = $40K-$60K; 5-10 small-employer payroll clients at $400/month recurring plus $3K average setup = $39K-$87K; 2-5 estate engagements = $5K-$50K. Total Year-1 revenue $84K-$197K; founder draw $50K-$90K.

Year 3 stabilized (possibly one part-time admin): 200-300 individual returns at $650 average = $130K-$195K; 25-40 small-employer payroll clients at $400/month recurring = $120K-$192K; 10-20 estate engagements = $25K-$200K. Total Year-3 revenue $275K-$587K; founder draw $110K-$180K.

Mature 5-plus year (founder + 1 part-time admin + 1 part-time preparer): 300-450 individual returns at $700 average = $210K-$315K; 50-75 small-employer payroll clients at $400/month recurring = $240K-$360K; 20-35 estate engagements = $50K-$350K. Total mature revenue $500K-$900K (working range $400K-$900K consistent with the affluent-residential sizing). Founder draw mature $140K-$220K.

Initial-capital deployment $40K-$150K — lowest capital outlay on the Campbell slate. Laptop + monitor + secure office workstation $3K-$5K. Tax-preparation software (Drake Tax, UltraTax, ProSeries, or Lacerte single-seat license with KY + OH state modules + multi-state e-file) $2K-$7K Year 1. Practice-management plus document-management software (Canopy, Karbon, or similar) $1.5K-$4K Year 1. Payroll software (Gusto, OnPay, or QuickBooks Online Payroll partner-tier) pass-through to clients; founder access $50-$200 per month.

One-room office lease (Fort Thomas, Newport, Cold Spring, Highland Heights, or Alexandria — co-working or single-office storefront) $800-$2,000 per month, $10K-$24K Year 1. Workers'-compensation policy (founder-only or 1-employee minimum) $400-$1,200 per year. Errors-and-omissions plus professional-liability insurance (CPA / EA practice $1M-$2M limits) — the literal insurance noun set — $1,500-$4,000 per year. KY Board of Accountancy license + Ohio reciprocal license + firm registration + peer-review enrollment + PTIN + EA enrollment $1K-$3K Year 1 plus recurring. Continuing-education (KYCPA + OSCPA + NATP enrollments + courses) $1,500-$3,500 per year. Marketing (website + local-SEO + Fort Thomas / Cold Spring direct outreach) $5K-$15K Year 1. Working capital 3-6 months operating-expense buffer $15K-$40K.

Founder-only Year-1 operation is viable at the low end of the $40K-$150K capital band — home-office plus co-working-day-pass setup. Upper bound is a single-office storefront with full software stack plus 6-month working-capital buffer. The lane is the lowest capital outlay on the Campbell slate and the only Campbell candidate where founder-only Year-1 is plausible without prior-business cash flow.

• Kentucky Board of Accountancy (Frankfort) and Ohio Accountancy Board (Columbus)

  State-board CPA licensure and cross-state practice privilege

  Active in market

  Kentucky CPA licensure plus mobility under Uniform Accountancy Act section 23 substantial-equivalence. Ohio reciprocal CPA license and firm registration for Ohio-source services to Ohio clients. The peer-review enrollment threshold and the reviewer-pool sourcing at Northern Kentucky scale still need confirmation.
• IRS Office of Enrollment and IRS PTIN registration

  Federal Enrolled Agent credential and paid-preparer registration

  Out-of-county

  The Enrolled Agent credential is federal-only and works across both states without state-board licensure for tax-return preparation. A PTIN is required for any paid preparer. EA-only founders stay in the prep plus payroll-compliance lane and refer the estate-planning portion to an outside attorney.
• Cincinnati Income Tax Division, Kentucky Department of Revenue Individual Income Tax and Employer Withholding, and Ohio Department of Taxation Individual Income Tax and Employer Withholding

  Multi-jurisdictional tax administration

  Active in market

  Cincinnati Income Tax Division handles the municipal-tax rate, employer registration, refund-claim mechanics, and remote-work sourcing guidance; the 1.8 percent rate cited here still needs confirmation. Kentucky uses Form 740 and Pub 740 for the city / occupational-tax credit and Form 42A809 for the reciprocity certificate. Ohio uses Forms IT-1040, IT-2023, and IT-4.
• Kentucky Society of CPAs, Ohio Society of CPAs, National Association of Tax Professionals, National Association of Certified Public Bookkeepers, and the AICPA Tax Section

  Professional associations, continuing education, and cross-river referrals

  Out-of-county

  The Kentucky Society of CPAs Northern Kentucky chapter and the Ohio Society of CPAs Cincinnati chapter run cross-river practice-development referrals. The National Association of Tax Professionals Kentucky chapter runs EA-focused continuing education. The Bookkeepers association handles sub-CPA bookkeeping and payroll add-on credentialing. The AICPA Tax Section runs multistate practice continuing education.
• NKU Haile College of Business — Accounting Department (Highland Heights)

  Graduating-class founder recruiting and part-time-preparer pipeline

  Institution

  Northern Kentucky's proximate accounting program. Graduating-class size, CPA-exam pass rate, and internship-to-hire pipeline need confirmation. A Year-3 part-time-preparer hire from the Haile pipeline cuts tax-season burnout risk.
• Cincinnati USA Regional Chamber Tax Policy Committee and the Cincinnati City Manager's Finance Department

  Cincinnati-employer referral and municipal-tax administrative escalation

  Out-of-county

  The Chamber's Tax Policy Committee is the Cincinnati-employer small-business referral channel. The City Manager's Finance Department is the administrative-escalation surface for refund-claim audit defense.
• H&R Block, Jackson Hewitt, Liberty Tax, TurboTax, Cash App Tax, FreeTaxUSA, and the IRS Direct File pilot

  Automated and franchise tax-prep competitive set

  Out-of-county

  Automated products consistently miss the Cincinnati municipal-refund claim, hybrid-worker day counting, multi-state payroll, and estate-planning layers. Seasonal franchise staff handle single-W-2 reciprocity but miss the municipal-refund mechanics. The lane is the founder's procedural edge — complexity-adjusted fees, not price competition.

Two viable founder paths. (1) Returning-home professional with prior CPA-firm tenure (Big Four, regional firm, or solo-practitioner experience) seeking a Campbell-resident solo practice — Kentucky CPA license plus Ohio reciprocal practice privilege under Uniform Accountancy Act §23 substantial-equivalence is the cross-river credential pathway. (2) Existing operator with EA credential plus 3-plus years prior multistate tax-practice experience pursuing founder-launch — EA-only practice is fully viable in the prep plus payroll-compliance lane and refers estate-planning portion to outside counsel.

Credential gates plus character-and-fitness review. Cross-state CPA licensure requires the founder pass both KY Board of Accountancy and Ohio Accountancy Board character-and-fitness reviews; PCAOB and state-board-discipline records must be clean. EA enrollment runs through the IRS Office of Enrollment; PTIN registration required for any paid preparer. AICPA Tax Section continuing-education on KY-OH multistate tax practice is the founder-differentiation credential.

Year-1 client-acquisition mechanics. The Cincinnati-commuter Campbell-resident household is reached through Fort Thomas plus Cold Spring direct outreach (the affluent-residential catchment that carries the multi-W-2 plus hybrid-worker plus Schedule-C plus K-1 complexity); through small-employer Campbell-side trades and insurance-agency referrals (small-employer multi-state payroll setup); and through KYCPA Northern Kentucky chapter plus OSCPA Cincinnati chapter cross-river referral channels. Cincinnati USA Regional Chamber Tax Policy Committee is the Cincinnati-employer small-business referral channel. Year-1 founder draw of $50K-$90K assumes the founder operates on accumulated savings or partner income through the first tax season — the second tax season is when retention compounds and referrals stabilize.

Explicit non-PE. No platform-rollup arithmetic, no minimum-five-times-EBITDA add-on math, no enterprise-value-exit assumption. The lane is a single-practitioner services firm built on procedural-compliance fluency plus Cincinnati-municipal-refund-claim mechanics — relationship-and-credential-gated rather than capital-gated. The structural complement to Christian County's KY-TN no-reciprocity arrangement: Campbell's KY-OH bilateral state reciprocity removes the rate-arbitrage product, leaving the procedural-compliance product (complexity-adjusted fees, not rate-arbitrage premium) as the founder's lane.

• — Current Kentucky and Ohio reciprocity citations — Kentucky Department of Revenue guidance, Ohio Revised Code section 5747.05 (or successor), and any 2025 to 2026 bills proposing changes in either legislature.
• — The current Cincinnati municipal income-tax rate. Resolve the 1.8 percent versus 2.1 percent gap between this draft and our earlier working draft against Cincinnati Income Tax Division guidance.
• — Current Cincinnati hybrid-worker and remote-work sourcing guidance — day-counting rule, principal-place-of-work designation, and refund-claim mechanics — and any 2024 to 2026 procedural updates.
• — LEHD LODES commuter count from Campbell to Hamilton County, Ohio at the most recent vintage, with sub-county geocoding to the Cincinnati municipal limits.
• — The share of Campbell-resident Cincinnati commuters working hybrid versus full-time-on-site versus full-time-remote after the 2023 work-arrangement convergence.
• — Kentucky Board of Accountancy active-licensee count in Campbell and the Northern Kentucky region. Ohio Accountancy Board reciprocal-privilege count for Kentucky firms.
• — A named roster of Campbell-incumbent CPAs and Enrolled Agents in Fort Thomas, Cold Spring, Newport, Highland Heights, and Alexandria, and how many advertise multi-state reciprocity and Cincinnati municipal expertise versus single-state generalist work.
• — Cincinnati Income Tax Division refund-claim docket volume — annual hybrid-worker and reciprocity-error refund counts and median processing time.
• — Current Kentucky Pub 740 city / occupational-tax credit cap, eligibility, and computation formula.
• — Current Ohio Form IT-2023 mechanics, employer-handling procedure, and the 2025-tax-year version. Kentucky's parallel Form 42A809 mechanics.
• — NKU Haile College of Business accounting program — recent graduating-class size, CPA-exam pass rate, and internship-to-hire pipeline.
• — AICPA Tax Section continuing-education courses specific to Kentucky-Ohio multistate practice and the credentials they confer.
• — Kentucky Board of Accountancy peer-review enrollment threshold and reviewer-pool sourcing at Northern Kentucky scale.
• — Estate-planning and retirement-account state-sourcing case law and ruling letters — federal P.L. 104-95, IRC sections 3121(v)(2) and 457, and Kentucky and Ohio Department of Revenue letter rulings on cross-state pension and deferred-compensation sourcing.

Tonight, this week, this month — in that order. Each step produces a yes/no or a number, not a deeper understanding.