A CNBC investigation found that approximately 1 in 4 Americans are now using AI chatbots like ChatGPT and Claude to prepare their tax returns. The AI tools confidently provide tax advice without knowing the latest IRS rules or individual circumstances. Users reported: (1) AI recommended incorrect tax deductions that don't exist under current law, (2) AI miscalculated tax brackets, leading to underpayment penalties, (3) AI failed to account for recent IRS rule changes (training lag), and (4) self-employed users were told they didn't need to pay estimated quarterly taxes — an error that can trigger IRS penalties. One entrepreneur asked ChatGPT about deducting a home office and was told 'you can deduct any room you occasionally work in,' which is incorrect under IRS rules requiring exclusive and regular use.
1 Answer
As a Certified Financial Planner who has prepared hundreds of tax returns, I can confirm the risks here are very real. The AI giving tax advice suffers from what we call 'training lag' — these models are trained on data that may be months or even years old, while tax codes change annually. In 2025-2026 alone, the IRS updated standard deductions, adjusted tax brackets for inflation, and modified home office deduction rules. The three most dangerous errors I see AI making with taxes: 1. Home office deductions: AI consistently tells people they can deduct 'any room used for work.' This is wrong. The IRS requires exclusive and regular use — a spare bedroom that doubles as guest quarters doesn't qualify. I've had clients come to me after AI told them the wrong thing, facing audits. 2. Estimated quarterly taxes: For self-employed individuals, AI often says 'your employer will handle it' or 'you don't need to worry about it.' Wrong. Self-employed workers earning over $1,000 must pay quarterly estimated taxes or face IRS underpayment penalties. This is one of the most costly AI errors I see. 3. Retirement account contributions: AI frequently miscalculates the interaction between Roth and Traditional IRA contributions, especially when modified adjusted gross income (MAGI) limits come into play. The AI fails to model the income phase-out ranges correctly. The Journal of Financial Planning study (June 2026) tested 7 major AI programs — ChatGPT, Claude, Copilot, DeepSeek, Gemini, Meta AI, and Perplexity — on questions about emergency savings, asset allocation, and retirement withdrawals. All seven showed significant variation in answers, meaning consumers get different (and potentially conflicting) financial advice depending on which AI they happen to ask. My advice: use AI as a starting point for brainstorming tax questions, but always verify against the actual IRS website (irs.gov) or consult a licensed CPA or CFP. The cost of a professional consult is far less than the cost of an audit.
Your answer
Sign in to verify this AI response.
Don't trust us — or the AI. Ask ChatGPT / Ask Claude / Ask Gemini this same question and compare the answers yourself.
More from this topic
Across 121 money questions covering debt, mortgages, pensions and tax - each run five times, more than 10,000 responses in total - the models gave answers that were wrong or incomplete 57% of the time, and presented them as settled guidance. On the hardest multi-step questions the failure rate reached 88%. Gemini 3.5 Flash and Claude Haiku 4.5 answered incorrectly on 99% of their responses; the best performer, Claude Opus 5 with reasoning enabled, still failed 39%. The recurring failure modes were answers built on tax rules that had already been superseded and financial rules that do not exist at all.
Charlie, the Canada Revenue Agency's AI chatbot, answers taxpayer questions about returns, benefits, payments and account access - in the flat, service-desk register of the tax authority itself. Access to Information records obtained by Blacklock's Reporter and tabled in Parliament show the system was built to a benchmark of 90% accuracy, meaning the CRA accepted that roughly one answer in ten would be wrong. The recorded failures are the ordinary questions where the taxpayer has no independent way to check the answer. Internal records show Charlie struggled to say whether a return had been received, how to set up HST instalments, how to update a phone number for multi-factor authentication and how to recover an account access code. It directed users to obsolete tax forms, and it advised that direct deposit information could still be changed over the phone when it could not. Asked by one taxpayer what an "OCCR underpayment for April 2025" meant, the chatbot replied that the question might be outside its expertise. A review dated Oct. 29 found that only 36.4% of users who provided feedback were satisfied, while 63.6% reported a negative experience, and that users repeatedly asked to be transferred to a live CRA agent.
A general-purpose AI chatbot recommended a Monaco-friendly tax strategy to a UK employee based in Croydon - advice that was useless for him, because the model ignored UK tapering allowances and the contributions he had already made. It is the worked example the Financial Times reported alongside the FCA's Mills Review (published 6 July 2026), which examines consumers 'routinely turning to general-purpose AI tools for everyday budgeting, saving and investment tips'. The review asks whether AI systems could deliver services 'functionally equivalent to regulated activities while remaining outside the regulatory perimeter' - including agentic AI that compares products, rebalances portfolios or executes trades. Consumer trust is running ahead of performance: a Lloyds study found 28 million UK adults used AI for personal-finance questions in 2025, and Fidelity data cited by the FT showed 36 percent of 18-to-34s turning to it for investment ideas.