It is me again, I'm 90% sure I'm going to head back to the UK when my lease runs out here (end of September of this year) but I am unsure of whether I should get my US citizenship (which would likely require me to remain in the country a few extra months) - although I have anxieties about returning I highly doubt I'd ever move back to the States - but maybe I should get my citizenship just to be sure.

My questions are: Once you are a citizen, is there a certain time you have to stay in the US before moving back to the UK? Has anyone got their citizenship and then left immediately after? Have you come across any problems doing this and returning to the States (such as just for a holiday)?

Lastly - I understand that you don't have to pay income tax if you earn less than $85000 a year - if you do earn more than this do you then get taxed doubled from there after?

Cheers everyone! Your input has been invaluable and it's very refreshing to hear from people who have had similar experiences and lived the expat life!

Gaining an extra citizenship is always worthwhile if it's an option. Not just for yourself but any future generations as well.

Once you're a citizen, that's it. But as you need to enter and exit the US on a US passport, you'll need to apply for one before you depart.

You have to file a tax return with the IRS every year - that doesn't necessarily mean you'll be taxed though. I'm not familiar with the thresholds, but I understand it's pretty high e.g. you have to be earning a fair whack before it kicks in.

This is actually quite interesting. I suppose the flip side of citizenship-dual/c is that it comes with strings.

I never considered it in 36 years in Aus. Whether right or wrong (a whole other debate!) I never felt Australian in any way and thus refused to become Australian in any way. I knew full well that if the opportunity to leave ever presented itself it would be a one way; I would never return.
And just in case;.......I MEAN I would never return..

BUT: you are younger and have the option to travel/settle. IF you have no philosophical objections to taking up DC, and there is no real threat of being slugged on tax; then give it serious thought.

At my age; never means never. At yours? you have a whole lifetime ahead of you, never does not necessarily mean never!

Currently the foreign earned income exclusion is $97,000 and after that amount, foreign tax credits can be used to offset US taxes owed. Since income marginal tax brackets in Europe are normally higher than the US, generally no US tax is owed no matter the amount of foreign earned income.

The isn't an exclusion for unearned income (primarily capital gains, dividends, and interest) but normally most countries in Europe (excluding Switzerland) have a higher tax rate on unearned income then the US so normally any US taxes owed will be offset by those foreign tax credits from the unearned income.

If you plan to live in a tax haven country, that is your greatest chance of having to pay US income taxes. However you will not normally be doubled taxed but pay the highest tax of either country after the foreign earned income exclusion. Some countries such as some Caribbean tax haven islands do not have a tax treaty with the US and then only the foreign earned income exclusion can be used and not foreign tax credits for either earned or unearned income.

One main tax issue that could possibly occur in the future is that the UK does not tax the gain on the sale of a primary residence but the US taxes the gain (profit) at a maximum 15% after an exclusion of $250,000 or $500,000 if it was your primary residence for at least 2 of the previous 5 years before it is sold. As an example, you purchased a home for $200,000 and sold it twenty years later for $800,000 and the exclusion was $500,000, you would have a US taxable income of $100,000 at a maximum of 15% ($800,000 - $200,000 = $600,000 gain - $500,000 exclusion = $100,000 US taxable income). The exclusion can be used every time you sell a primary residence so if you sold you home every 10 years and the gain was less than the exclusion each time, you wouldn't owe US taxes.

Another possible issue is estate taxes upon death. Currently the US has an unlimited exclusion when the estate is passed from spouse to spouse but has a $5 million total exclusion when it is passed to anyone else including children.

My sentiments exactly - I said I would never become a US citizen as long as I didn't feel the same way about the US as I do England. I never have and at this point, don't think I ever will.
What is sad is the we are retired now - both receiving SS (mine is only half of the full amount due to the job I had for 20 years. My husband works a small part time job delivering plants for a grower around here and yet, we still have to pay over $1,000 in income tax a year as well as money being taken out of our medicare to cover what medicare doesnt. We are worse off now than before he retired as his company paid all medical insurance and we usually managed to get something back from filing our SS each year.