Before running for the hills (or for an accountant), take a look at some of the basics:

French Déclaration des revenues 2006
This year, discover the new pre-completed form n° 2042! The government kindly fills out your income information to “simplify” the process. Beware: carefully verify the information and make adjustments wherever necessary. This form will be mailed in early May for a filing deadline currently set for May 31, 2007. If you don’t receive the form, request it. The wealth tax is to be self-assessed separately.
If you file your tax return electronically, you will receive both a filing extension and a 20 € rebate. www.impots.gouv.fr

U.S. Expats
The United States taxes citizens no matter where they live. Thus, Americans and green card holders residing in France often have to file both French and American (Form 1040) tax returns.
Double filing does not necessarily mean double paying. A complicated system of tax credits and exemptions ensures that, as a rule, income is not taxed twice. Typically, the first $80,000 of employment income earned abroad are exempt from U.S. taxation (see IRS Form 2555 for qualifications). You must file a Form 1040 if your annual gross income in 2006 was over $8,450 (individual) or $16,900 (married, filing jointly).
This year’s deadline is April 17, 2007, but overseas residents receive an automatic extension until June 15, 2007 for filing only: pay taxes owed by April 17 to avoid penalties and interest.
The IRS office in the U.S. Consulate at 2, rue St. Florentin, Paris 1, (M° Concorde). offers free assistance from 9 a.m. to noon, Monday through Friday (walk-in), and from 9 a.m. to noon and 1.30 to 3.30 pm (telephone). www.amb-usa.fr/irs/irs.htm .

UK Expats
If you are in the UK for 183 days or more in any one tax year you pay tax in Great Britain. You are deemed a non-resident by leaving the UK for one complete tax year or more. If you visit the UK for more than 91 days each year for four years, you can become a UK resident again.
If you are a French resident but perform your duties in the UK, your employment income is taxable in the UK, not France. Your employment income will be taken into account in determining the rate at which your other income is taxed in France. +44 (0)207 438 6425

Canadian Expats
Living abroad but maintaining residential ties in Canada, makes you a Canadian resident for tax purposes. If you live part of the tax year in Canada, you must report income from all sources on your Canadian tax return. Non-residents are taxed only on income from Canadian sources. Canada Revenue Agency Web site: www.cra.gc.ca or Publication T4131, Canadian Residents Abroad.