Senior Full-Stack Engineer — AI Agent Systems

About this role

Senior Full-Stack Engineer - AI Agent Systems

TaxFlow · Accounting & Taxation platform · Full-time · Remote (USA-based)

About TaxFlow

TaxFlow is a tax-preparation platform for CPA firms. We take the most document-heavy, deadline-driven workflow in professional services - the annual tax return - and rebuild it around AI: documents arrive, get classified and extracted by an agent pipeline, land in a per-return workspace ("binder") as reviewable, cited values, and flow through preparation workpapers to the firm’s tax software. Firms keep the judgment; the platform does the shuffling.

This is real-money, real-compliance software. Taxpayer PII, IRS Pub 4557 / FTC Safeguards obligations, audit trails, immutable records. Accuracy is not a nice-to-have - it is the product.

The role

You’ll be the second engineer, working directly with the founding team across the whole platform - and you’ll do it in an agent-native workflow: we build with parallel AI coding agents, where engineers set direction, write sharp specs, review rigorously, and orchestrate agent teams rather than typing every line. If your instinct on a complex migration is "spec it precisely, fan it out, verify adversarially," you’ll feel at home.

Your center of gravity:

• **AI / agent systems (the core of the role).** Design and harden the document-intelligence pipeline: multi-step agent harnesses for classification, extraction, and review of tax documents (W-2s, K-1s, 1099s, organizers, prior-year returns); prompt/tool design; structured outputs; confidence scoring and citation of extracted values; evals and regression suites so quality is measured, not vibes.
• **Backend.** Postgres data modeling in a strictly multi-tenant schema (70+ tables, DB-first with Drizzle), server functions, background job orchestration (Inngest), document storage (R2/S3), and vendor integrations - CCH Axcess import/export, IRS MeF, third-party extraction APIs - kept behind clean adapter seams.
• **Full-stack pro...