If you are interested in private practice as an attorney, having a CPA provides you with a knowledge base that will help you with any type of corporate law, including mergers & acquisitions, tax, real estate, general corporate, SEC filings, trusts & estates, and others. Someone who has practiced as an attorney and has a CPA could also work as in-house counsel for both private and publicly-held companies. In addition, many CFOs (Chief Financial Officers) have both a JD and a CPA.
If you are interested in tax law, consider obtaining an LLM in tax as an option.
Either way, being a JD-CPA increases your options and marketability.
Most lawyers aren’t CPA’s, and most CPA’s don’t have law degrees. The dual combination could be quite a niche.