Should I leave USA on my US passport or can I use my UK passport.

It wouldn't matter what passport you used.

As SimCityAT has indicated, you can use either; the only advice I would offer is that whatever you use (you will have to disclose the issuing country and number when you check-in on-line), to use the same passport throughout your journey.  I once tried to be clever and use my UK passport on leaving the UK and my US passport at Dulles (to beat the queue); I really wish I hadn't bothered.

The only issue is that if you enter the US on your uk passport you will need the online visa waiver thing which costs about $20.

James Oliver wrote:

I am going to  UK for my cousins wedding in July and was wondering if I can leave the Usa on my UK passport..


I been reading conflicting reports not sure if its allowed..

Can I use my UK passport for booking my flight (British Airways )


Or would I need to use my US passport when leaving  The country ?

Actually there is no "border control" when leaving the country, so it's somewhat irrelevant.  However when you check-in, you'll want to show your UK passport so the desk agent knows you're clear to travel there as a UK passport holder.  For booking I would use the UK passport as well.

When returning to the USA however, use your USA passport at immigration control if you don't want to be held for secondary inspection.

Romaniac
Expat.com Experts Team

The leaving should be no issue at all save a different queue at immigration but you can probably use the UK passport for that (Will stamps be an issue?), but returning to the US is likely to be trouble free if you use a US passport.

romaniac wrote:

James Oliver wrote:

I am going to  UK for my cousins wedding in July and was wondering if I can leave the Usa on my UK passport..


I been reading conflicting reports not sure if its allowed..

Can I use my UK passport for booking my flight (British Airways )


Or would I need to use my US passport when leaving  The country ?

Actually there is no "border control" when leaving the country, so it's somewhat irrelevant.  However when you check-in, you'll want to show your UK passport so the desk agent knows you're clear to travel there as a UK passport holder.  For booking I would use the UK passport as well.

When returning to the USA however, use your USA passport at immigration control if you don't want to be held for secondary inspection.

Romaniac
Expat.com Experts Team

There is a security system known as Advanced Passenger Information (API) in use in the US and most EU countries; when you "check-in" for a flight from and to the UK (and US), you are required to provide your passport information (Country of Origin and document number); this information is provided by the airlines to the Security services of both countries - if you like, it's a soft form of Border Control.  If a passenger checks in with one document and then uses another for the return flight (or changes documents mid-flight), it will flag the system and the passenger will have to answer questions and may even be delayed.

There is a Wiki page about it here.

Cynic wrote:

romaniac wrote:

James Oliver wrote:

I am going to  UK for my cousins wedding in July and was wondering if I can leave the Usa on my UK passport..


I been reading conflicting reports not sure if its allowed..

Can I use my UK passport for booking my flight (British Airways )


Or would I need to use my US passport when leaving  The country ?

Actually there is no "border control" when leaving the country, so it's somewhat irrelevant.  However when you check-in, you'll want to show your UK passport so the desk agent knows you're clear to travel there as a UK passport holder.  For booking I would use the UK passport as well.

When returning to the USA however, use your USA passport at immigration control if you don't want to be held for secondary inspection.

Romaniac
Expat.com Experts Team

There is a security system known as Advanced Passenger Information (API) in use in the US and most EU countries; when you "check-in" for a flight from and to the UK (and US), you are required to provide your passport information (Country of Origin and document number); this information is provided by the airlines to the Security services of both countries - if you like, it's a soft form of Border Control.  If a passenger checks in with one document and then uses another for the return flight (or changes documents mid-flight), it will flag the system and the passenger will have to answer questions and may even be delayed.

There is a Wiki page about it here.

Thank you all for the replies..

In response to this if I leave the usa on my Uk passport  I would need to book return flight with my uk passport ?
When I got back to the usa I would use my usa passport.

If you intend to book 2 separate flights, then there is no reason why you shouldn't do that; however, you should check first whether you get a better deal by booking a return flight; when I worked in the airline industry (albeit some years ago now), you got a much better deal with a return booking.