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Claude hallucinated a German reverse-charge threshold — posting so nobody else gets caught

DADr. Anna Schmidt, StB·1d ago·germany-vat-return.md·DE

posting as a warning. prepping a UStVA for a Freiberufler client who invoices a Swiss consulting firm. asked Claude (plain chat, no OpenAccountants skill installed — lazy of me, i know) about the reverse-charge treatment.

it told me there's a €10,000 de minimis threshold below which §13b UStG doesn't apply for B2B services to non-EU recipients. confident, no citation.

there is NO such threshold. §13b applies from the first euro for B2B services where the place of supply is outside DE. i almost filed an UStVA with incorrect output-VAT treatment because of that.

when i reran the exact same question with the germany-vat-return skill installed (Claude Code + the skill as context), i got the correct answer with a cite to §13b Abs. 2 Nr. 1 UStG and the BMF-Schreiben on place-of-supply rules.

lesson: never ask a naked LLM for a threshold. always run with a dated, cited skill. i got lucky because the number looked suspicious — next time it might not.

4 replies

SCSarah Chen, CPA·1d ago

identical experience on US side. asked plain Claude what the 2025 §179 limit was — got $1,160,000 confidently stated. real number is $1,220,000 (Rev. Proc. 2024-40). $60k miss at a 37% bracket = ~$22k of missed deduction.

rule i follow now: any dollar/euro threshold gets run through a skill or verified against the primary source. never take the LLM's number on faith.

YTYuki Tanaka, 税理士·23h ago

同じ経験あります。asked Gemini for the 2割特例 end date, got "2023". actual end is 2026年9月30日. two-year error. skills with explicit effective dating saved me from filing wrong.

PDPierre Dubois, Expert-Comptable·20h ago

c'est exactement pourquoi la règle "cite la statue ou tais-toi" est tellement importante. naked LLM = danger. skill + agent = outil utile.

JMJames Mifsud, CPA·17h ago

this is why the self-check section at the end of every OpenAccountants skill is so valuable — it forces the agent to state "this answer relies on [threshold X] effective [date Y]". makes hallucinations visible.

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