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In order to become a CPA in the United States, the candidate must sit for and pass the Uniform Certified Public Accountant Examination (Uniform CPA Exam), which is set by the American Institute of Certified Public Accountants and administered by the National Association of State Boards of Accountancy. The first law establishing the CPA designation was passed in New York on April 17, 1896.^[2]
Eligibility to sit for the Uniform CPA Exam is determined by individual State Boards of Accountancy. Typically the requirement is a U.S. bachelors degree which includes a minimum number of qualifying credit hours in accounting and business administration with an additional 1 year study. This requirement for 5 years study is known as the "150 hour rule" and has been adopted by the majority of state boards, although there are still some exceptions (e.g.California). This requirement mandating 150 hours of study has been adopted by 45 states.
The Colorado State Board of Accountancy allows Chartered Certified Accountants (ACCA), together with Chartered Accountants from eligible jurisdictions (Australia, South Africa, Canada, Ireland, New Zealand) automatic eligibility to sit for the Uniform CPA Exam as a Colorado candidate. As of December 9, 2009, ACCA members are not automatically eligible to sit for the Uniform CPA Exam.
Certain overseas qualified accountants seeking to become U.S. CPAs may be eligible to sit for the International Qualification Examination as an alternative to the Uniform CPA Exam.
The Uniform CPA exam tests general principles of state law such as the law of contracts and agency (questions not tailored to the variances of any particular state) and some federal law as well.^[3]

Certified Public Accountant (CPA) is the statutory title of qualified accountants in the United States who have passed the Uniform Certified Public Accountant Examination and have met additional state education and experience requirements for certification as a CPA. Individuals who have passed the Exam but have not either accomplished the required on-the-job experience or have previously met it but in the meantime have lapsed their continuing professional education are, in many states, permitted the designation "CPA Inactive" or an equivalent phrase. In most U.S. states, only CPAs who are licensed are able to provide to the public attestation (including auditing) opinions on financial statements. The exceptions to this rule are Arizona, Kansas, North Carolina and Ohio where, although the "CPA" designation is restricted, the practice of auditing is not.
Many states have a lower tier of accountant qualification (below that of CPA), usually entitled "Public Accountant" (with designatory letters "PA"). However the majority of states have closed the designation "Public Accountant" to new entrants, with only about 10 states continuing to offer the designation. Many PAs belong to the National Society of (Public) Accountants.
Many states prohibit the use of the designations "Certified Public Accountant" or "Public Accountant" (or the abbreviations "CPA" or "PA") by a person who is not certified as a CPA or PA in that state. As a result, in many circumstances, an out-of-state CPA is restricted from using the CPA designation or designatory letters until a license or certificate from that state is obtained.
Texas additionally prohibits the use of the designations "accountant" and "auditor" by a person not certified as a Texas CPA, unless that person is a CPA in another state, a non-resident of Texas, and otherwise meets the requirements for practice in Texas by out-of-state CPA firms and practitioners.^[1]
Many other countries also use the title CPA to designate local public accountants. The equivalent in Commonwealth countries is the chartered accountant.

what the primary difference is between the UK and US certification model.
It is interesting to note that this same difference is also reflective of the general educational ideology of both countries, and pours into the business and corporate culture. That said, it is safe to say that public accounting certifications in both countries, the Chartered Accountancy (ACA) licensed by the Institute of Chartered Accountants in England and Wales (ICAEW) in the UK and the Certified Public Accountant (CPA), licensed by the American Institute of Certified Public Accountants (AICPA) in the US, follow a rather similar pattern. They start with pretty basic level papers and work their way upto technical financial accounting with the ultimate goal of preparing you for conducting audits, and work experience is a requirement before you can even sit for some of the papers.
However, when it comes to management accounting certifications for industry, there is a massive difference in the way the two countries market and manage the qualifications. In the UK, CIMA, ACCA, AAT etc. are all guaged toward accounting and non accounting college majors / graduates alike. They start with the basic, classic, outdated financial and cost accounting concepts, and work their way up to fancy financial and management reporting. The early papers are a waste of time for students who are accounting majors in university, the these certifications don’t give it any value. There are no experience or educational requirements before you can sit for the exam. The exams are driven to help you memorize concepts, rather than understand and apply them. The study material is not very practical in approach, and as a whole, the quality of business relevant financial education you get from these certifications in the UK may not really be that good. However, they are still considered vital to the stamped-paper, bureaucratically obsessed, paper-pushing UK market.
In the US, however, the standard is different. Take the Institute of Management Accountants, for instance. They offer to Financial Management Certifications: the Certified Management Accountant (CMA) and the Certified Financial Manager (CFM). Both Certifications require accounting degrees (like the CPA) or several years of experience in the accounting industry. The reason: Management Accounting Certifications are not geared toward non-accounting majors. The content is technical, and the idea is to further train accountants help enhance their knowledge and application of management accounting concepts and financial accounting regulations. With that in mind, the IMA does not flood you with waste of time, silly, O’Level based accounting papers that discuss the basics of debits and credits. For both Certifications, the IMA has a total of 6 papers you need to pass. However, and this is where the primary difference flows through into corporate America, you need 78% to pass IMA exams, whereas you need only 50% to pass CIMA papers? Why? Well, it would seem like CIMA is just trying to churn out accountants; people who can do the basics of accounting. IMA, on the other hand, is aiming for financial managers: accountants who understand the ramifications of various financial and management accounting principles.
I, personally, have been disappointed with the content of CIMA in the UK. You walk away with very little, and the education is highly impractical for business purposes. IMA, on the other hand, focused on know what you did well, and the exams were based more on your understanding and application of concepts, rules, and regulations rather than committing concepts and definitions to memory. I would say the IMA definitely offers better knowledge in less time and challenges you more to succeed while providing more practical and corporate education. CIMA content desperately needs an overhaul given the state of the business world in the 21st century.