Ben Franklin said, "Nothing is certain, except death and taxes." For tax professionals, that means their skills will always be in demand. The tax service business is an almost year-round opportunity for retirees who enjoy tax work and marketing their services. It's great for retired CPAs and anyone who likes to crunch numbers or pore over obscure federal and state legal codes.
To work as a tax professional, a person must register with the IRS, pass a proficiency exam (this does not apply to licensed attorneys, CPAs or supervised preparers who don't sign returns but are directly supervised by an attorney, CPA or enrolled agent) and complete a certain amount of annual continuing education training. Tax companies such as H&R Block provide tax preparation courses for beginners, although it's important to read the fine print associated with these programs because many prohibit students from going on to work for other companies for a certain period of time [source: IRS].