Does the tax treaty between the US and UK mean you only pay tax once living in the UK?

w00519773

I am a UK resident with a paper trading account with interactive brokers: https://www.interactivebrokers.co.uk/.  I am usually a passive investor who invests for the long term in my pensions and stocks and shares ISA.  However, I may use Interactive Brokers to buy shares with the disposable income I have left after investing for the long term and paying off all my bills.
Interactive Brokers tell me that I can invest in shares in any country I want (if I want to buy US shares/ETFs then I have to fill in an IRS W8-BEN form).  I am only really interested in the UK and US.  I am trying to understand what tax liabilities there are if I invest in the US.  My research is telling me that there is a "tax treaty" between the UK and US meaning you only pay tax on dividends; capital gains etc once (at the UK rate).  However, I wanted to check this.  Is that still correct with Brexit in the mix etc? I would be interested to hear from other UK investors/traders who buy US shares/ETFs etc and how taxes affect you. 
Here are two scenarios:
1) Buy and sell five stocks in one day.
2) Buy one stock today and sell it in 11 months.
Also how does contract for difference fit it here? With CFDs is it necessary to fill in a W8-BEN and are the tax concerns any different to share dealing?
Again I understand all of the risks - I am just trying to understand what my options are at this stage.

eskbanker

Holders of US shares have US tax deducted from their dividends but the treaty allows this tax to be offset against UK income tax liabilities.

Thrugelmir

It is mandatory to complete a W8-BEN if you wish to trade US shares in the UK.  Completing a W8-BEN reduces US tax deductions such as was would be made on dividends. Any further tax liabilities would be standard UK ones, which would be dependent upon the wrapper the investments are held in. 

w00519773

Thrugelmir said:

Completing a W8-BEN reduces US tax deductions such as was would be made on dividends. 

Thanks.  So there would be more taxes to pay if investing in US stocks/ETFs in comparison to UK stocks/ETFs?

Thrugelmir

w00519773 said:

Thrugelmir said:

Completing a W8-BEN reduces US tax deductions such as was would be made on dividends. 

Thanks.  So there would be more taxes to pay if investing in US stocks/ETFs in comparison to UK stocks/ETFs?

No you wouldn't. 

w00519773

Thrugelmir said:

w00519773 said:

Thrugelmir said:

Completing a W8-BEN reduces US tax deductions such as was would be made on dividends. 

Thanks.  So there would be more taxes to pay if investing in US stocks/ETFs in comparison to UK stocks/ETFs?

No you wouldn't. 

Thanks.  How does Contract for Difference fit in here in comparison to share dealing? I assume that would be the same i.e. no additional taxes for US shares/EFTs?
Again I understand the risks of CFDs; just trying to understand my options at this stage.

Steve182

w00519773 said:

Thrugelmir said:

w00519773 said:

Thrugelmir said:

Completing a W8-BEN reduces US tax deductions such as was would be made on dividends. 

Thanks.  So there would be more taxes to pay if investing in US stocks/ETFs in comparison to UK stocks/ETFs?

No you wouldn't. 

Thanks.  How does Contract for Difference fit in here in comparison to share dealing? I assume that would be the same i.e. no additional taxes for US shares/EFTs?
Again I understand the risks of CFDs; just trying to understand my options at this stage.

You are liable for CGT on profits on CFDs. You would pay no CGT at all if you are a UK resident and just did spread betting on the share price instead as there is no betting tax in the UK. That's what I do for a bit of added interest. Less than 1% of my portfolio I would add. I use an IG account. 

w00519773

Steve182 said:

w00519773 said:

Thrugelmir said:

w00519773 said:

Thrugelmir said:

Completing a W8-BEN reduces US tax deductions such as was would be made on dividends. 

Thanks.  So there would be more taxes to pay if investing in US stocks/ETFs in comparison to UK stocks/ETFs?

No you wouldn't. 

Thanks.  How does Contract for Difference fit in here in comparison to share dealing? I assume that would be the same i.e. no additional taxes for US shares/EFTs?
Again I understand the risks of CFDs; just trying to understand my options at this stage.

You are liable for CGT on profits on CFDs. You would pay no CGT at all if you are a UK resident and just did spread betting on the share price instead as there is no betting tax in the UK. That's what I do for a bit of added interest. Less than 1% of my portfolio I would add. I use an IG account. 

Thanks.  I understand the difference between CFDs and spread betting.  It would still be good to know if there was a tax difference between trading/investing CFDs in US and UK (as a uk resident).  Based on Thrugelmirs' answers I believe the answer is no.