UK Tax implications of moving to a third country

So a few things lately about living in the UK have not filled me with unadulterated joy, and I have begun to think about where we might move to in the future.  I notice that even after leaving the UK we may be required to complete UK tax returns for up to 5 years if we have ‘foreign pensions’. Well, we have SS, company DB pensions, IRAs and 401ks.  Where would we stand from a UK taxation perspective? I am a British born dual citizen, I’m sure my domicile would be UK.  My husband is a US citizen.

So a few things lately about living in the UK have not filled me with unadulterated joy, and I have begun to think about where we might move to in the future.  I notice that even after leaving the UK we may be required to complete UK tax returns for up to 5 years if we have ‘foreign pensions’. Well, we have SS, company DB pensions, IRAs and 401ks.  Where would we stand from a UK taxation perspective? I am a British born dual citizen, I’m sure my domicile would be UK.  My husband is a US citizen.

Where have you read that?  I would look at double taxation treaties between the countries you are considering.

I was living in the USA for 10 years while drawing a UK pension and then also US pensions. While living in the USA my domicile was in the USA, even as a Green Card holder, because I had no home in the UK and the vast bulk of my income was in the USA. Even if I was still living in the USA when I started receiving my UK OAP, the tax treaty quite clearly states that it would only be taxed in the USA.

My brother is living in Australia, receiving his UK OAP, and also a private pension from when he lived there and he doesn't pay UK taxes on anything.

Where have you read that?

Gov.uk
‘When to report your income to HM Revenue and Customs (HMRC)
You usually have to send a Self Assessment tax return if:

you rent out property in the UK
you work for yourself in the UK
you have a pension outside the UK and you were UK resident in one of the 5 previous tax years
you have other untaxed income
You do not need to report your income to HMRC if you’ve already claimed tax relief under a ‘double-taxation agreement’.

I’m not so much concerned that it would end up costing me money as that we’d have to file even more returns.

Gov.uk
‘When to report your income to HM Revenue and Customs (HMRC)
You usually have to send a Self Assessment tax return if:

you rent out property in the UK
you work for yourself in the UK
you have a pension outside the UK and you were UK resident in one of the 5 previous tax years
you have other untaxed income
You do not need to report your income to HMRC if you’ve already claimed tax relief under a ‘double-taxation agreement’.

I’m not so much concerned that it would end up costing me money as that we’d have to file even more returns.

You may be correct, I have never lived outside the UK while receiving a foreign pension having previously been a resident of the UK  in one of the previous 5 years. however, all the time I have been resident in the UK while receiving my foreign pensions I have been paying HMRC taxes on those pensions while claiming tax relief under a double taxation agreement so that clause should let me out from filing HMRC taxes if I moved overseas.