As a veteran tax CPA, I think LLMs can be very good at preparing taxes but I would not trust them to complete a tax return start to finish. An LLM that can take data from tax documents and input that data into the correct boxes of tax preparation software has no need for math, it just has to identify data in a pdf, spreadsheet, or handwritten note and transcribe that data to the correct box in professional tax software that then does the math. In your typical local CPA firm, an LLM could replace the unlicensed preparers/interns/early career stage CPAs in filling out the return for the experienced professional to review and adjust according to their specialized knowledge. As with many industries, I think the LLMs are suited at replacing entry level automated turks but lack the skills necessary to fully complete the project.