Passport Question

Next Sunday 6th June I'll be traveling via france to Boston Mass for holidays with my relatives there..
My question is this..
I always have both US and Uk passports with me and use both.
However Im not sure when I use the UK one when traveling within the EU ..
Would i use the UK one to leave Scotland and enter France and then my us one leaving france and entering the US. Then use US one leaving Us and the UK one entering france and back to Scotland?  I think thats right but just wanted to check.
Thanks
Kay

It sounds like you have dual citizenship? You don't really "use" a passport to leave a country, at least not in an immigration sense, although the airline or ship operators will want to see one as proof of ID, and if you prebooked and gave passport details, you would have to show the right one.

Legally, US citizens are required to use a US passport when entering the US and to have one in their possession when departing the US. (there is no formal immigration control when US citizens depart the US).

The UK requires you to use the UK one when entering the UK. Beyond these, you have a choice. Since France does not require either US or UK citizens to get a visa, I cannot see that it really matters which one you use on entering or leaving that country, except as mentioned above.

Ta for the info Trem.
I've often wondered all these years that i've had dual if I had been using the two passports correctly. So you have given me info that i didn't realise.
Thanks
Kay

It sounds like you have dual citizenship? You don't really "use" a passport to leave a country, at least not in an immigration sense, although the airline or ship operators will want to see one as proof of ID, and if you prebooked and gave passport details, you would have to show the right one.

Legally, US citizens are required to use a US passport when entering the US and to have one in their possession when departing the US. (there is no formal immigration control when US citizens depart the US).

The UK requires you to use the UK one when entering the UK. Beyond these, you have a choice. Since France does not require either US or UK citizens to get a visa, I cannot see that it really matters which one you use on entering or leaving that country, except as mentioned above.