From Wiki

[edit] ADVANTAGES

• Voting
  

Your chance to participate in steering America in the right direction.

• Retaining residency and avoiding deportation

Naturalisation is the only way to guarantee you have the right to remain in the US. PRs are at risk of losing their status if they spend long periods of time outside the US or commit certain, sometimes not very serious, crimes.

• Bureaucracy
  

Your dealings with the US immigration authorities finally come to an end and you no longer have obligations, for example, to inform them of your change of address. Also, you will release your spouse or joint sponsors from financial responsibility of sponsorship under the I-864.

• Government benefits
  

Some US permanent residents are restricted from access to public benefits, especially from receiving them whilst abroad. This is a continuing and deepening trend. This can include access to Social Security benefits.

• Immigration for family members
  

Unlike USCs, green card holders cannot sponsor parents or siblings, and USC receive priority for spouses and children.

• Running for political office
  

Many types of elected positions require the officeholder to be a USC.

• Tax
  

USCs and PRs are not always treated the same for tax purposes. This is particularly true for estate taxes. If both parties are USCs married to each other, then the estate passes from one party to the other without taxation. If both parties die, then the estate passes to whoever is named in the will or determined by probate court. In 2005, the first $1.5M are not taxed. From 2006 to 2011, the first $2M is protected from estate taxes. Beyond 2011, if congress does not extend the repeal, then only the first $650K is free of taxes. However, for non-citizens, the rules are different and any estate over $650K is taxable.

• Federal grants
  

Some federal grants are only available to US citizen applicants.

• Federal jobs
  

Most federal government jobs and many state/local government jobs, require the applicant to be a USC. Most (but not all) state and local police forces, for example, require USC to become a police officer.

Some government-related jobs in corporations require a USC, especially in the energy and defense sectors.

Security Clearance, for the above type of jobs, with citizenship, you can have a higher level, but don't forget that having ties to the UK via friends, family, property etc might still limit the level of clearance you may gain.

• US Passport
  

As a USC you are entitled to a US passport (which may have better visa-free travel) and to consular protection from American missions overseas. However, US consular protection is not available in any other country of which you are a citizen.

• NAFTA Rights
  

USCs have simplified access to work permits in Canada and Mexico due to NAFTA treaty provisions.

• Citizenship for non-US born children
  

As a naturalized USC you will be able to pass on US citizenship to children born outside the United States.

• Firearms
  

Most states allow Green Card holders to possess firearms, but some (eg Washington State) require any non-citizen to have a permit. As a USC you will be exempt from these requirements. Also, many states will only issue "concealed carry" permits to USC applicants. Furthermore, the rights of Green Card holders to own and use firearms could be removed by federal legislation in future. As a USC your rights to own a firearm are protected by the Second Amendment.

• Professional Licensing
  

In a few states, one of which is Alabama, you may need to be a USC in order to get a professional license, such as become a Certified Public Accountant (CPA) in that state.

[edit] DISADVANTAGES

• Jury Duty
  

You can no longer escape this by ticking the non-citizen box

• Dual citizenship
  

For a small minority of people, there may be dual citizenship issues. For most Brits, this is a not a problem. (See: http://www.richw.org/dualcit/)

• Tax
  

You are now liable for US tax on your worldwide income if you leave the US. Unlike most other countries, US citizens pay tax on their worldwide income, regardless of where they are living. So if you move to the Cayman Islands and live there 20 years, you are still required to pay US taxes. This is a very important point to note. Tax Treaties with certain countries mean you will not be doubled taxed if you paid taxes on monies earned in that country to that tax authority.

Also note that if you wish to maintain your PR status while living abroad for a year or two and have the appropriate re-entry permit, you must continue to pay US taxes as proof of unabandonment of residency.

• Cuban holidays
  

Are now a no-no! (although this is also the case for green card holders and even temporary residents of the U.S.).