tax accountant
An accounting firm or individual specializing in tax-related accounting and advice.
A tax accountant is an accounting firm or person who specializes in tax-related work.
Tax-related work includes preparing tax returns and calculating tax liabilities. A general accountant can cover financial records and reporting more broadly, while the tax accountant's specialization is taxation.
A law firm provides legal services through lawyers. The boundary is not simply whether someone represents a taxpayer: the right to provide advice or representation depends on jurisdiction and professional qualification, and some tax accountants also have representation rights.