Claude + us-qbi-deduction skill nailed an SSTB phase-out edge case — worth flagging
counter-post to the hallucination threads. edge case for an SSTB client: taxable income right at the $394k MFJ threshold start, specified service (consulting).
ran Claude Code with us-qbi-deduction skill installed locally. fed it Schedule C numbers, W-2 wages, UBIA, asked for QBI computation with phase-out reasoning.
what it got right:
- identified SSTB from the business description (no prompting)
- applied the PHASED reduction formula under §199A(d)(3)(B), not the simplified "above threshold → zero" shortcut
- flagged that at client's exact income the reduction was ~78% complete, not full
- cited the worksheet in the skill, gave me the exact dollar reduction
- proactively noted that a $2k retirement top-up would clear the remaining phase and recover ~$3,100 of QBI deduction
would this have saved me the 20 minutes i spent verifying? no. as an independent error-catch layer? genuinely useful, and the citations meant i wasn't chasing phantom logic.
want to build a mental model of what the agent+skill combo actually does cleanly. anyone got similar wins?
4 replies
the pattern i keep seeing: skill + agent > naked agent for anything statutory. agent-alone is fine for generic explanation ("what is QBI?") but anything involving numbers or current-year thresholds needs the skill in context.
also: having the skill there means the agent CITES. clients love seeing a citation to §199A(d)(3)(B) next to a computation. makes the review call shorter.
similar win on a régime réel threshold question for a client who crossed mid-year. claude + france-vat-return skill knew the 2025 reform thresholds; naked claude was still citing 2023 numbers. the skill effectively "anchored" the agent in the current year.
Freiberufler KSK contribution interaction with the SE health insurance deduction — claude + the germany-vat-return + a Freiberufler-specific workflow i set up locally. would NOT trust a naked LLM with any of this. but with skills? reliably useful.
the win for me is speed on the boring bits — running the same phase-out math across 5 SSTB clients in a weekend. not exciting work but the skill + agent cuts the mechanical part from hours to minutes. the judgment calls still take the same time.
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