Accounting / Bookkeeping / Tax Firm Acquisition & SBA Underwriting Financial Model — Realization-Rate Bridge, Recurring CAAS Book, Tax-Season Cash Curve & DSCR (Excel + Google Sheets)

Realization-Rate Bridge + Recurring-CAAS-vs-Tax-Season Revenue-Quality engine. Most accounting-firm templates are startup/operating forecasts, and brokers anchor on "1x gross fees" of the *standard-rate* schedule. This is a single-firm acquisition underwrite built on the numbers a bank and a disciplined buyer actually use:

• Read the book on COLLECTED fees, not standard rates. Four service lines (recurring compliance/CAAS, annual tax prep, non-recurring advisory, attest), each written down by its realization rate → net collected fees. Blended realization ~89% (a standard-rate book overstates ~11%).
• DSCR true vs naive. A market-rate producer replaces the owner-biller + an explicit tech/transition reserve → true DSCR 1.43x next to the broker's naive 2.88x.
• Transfer-attrition down-case. Post-sale retention at the profession's 75–80% average instead of 90%, plus AI/fee compression → DSCR 0.66x, below the 1.25x floor (and the earnout clawback trips).

Plus: the tax-season cash curve counts the months where collections don't cover the bank (4 tax-season / 0 year-round CAAS); recurring-vs-lumpy re-rates advisory; SBA 7(a) capital stack with the seller-note standby lever, a goodwill $500k valuation-trigger flag, and a 5-year MOIC exit (no IRR).