Hi and welcome to Just Answer!a) if I have to file US tax returns and if soYes - as you are an US citizen - you filing requirements are same as for other US citizens - and - yes - you are required to report all your worldwide income.In additional if you have foreign bank accounts with the total value above $10,000 - you are a subject of FBAR reporting.. b) what tax I might be liable to pay. Are you able to enlightenment me on the issue?To determine your tax liability - if any - you need to file your tax return. Because you are a bona fide resident of the UK - you may claim a foreign earned income exclusion. However - if the same income is taxed in both countries - you may claim a credit for foreign tax paid on your US tax return - thus effectively will avoid double taxation. So your US tax liability would be minimal if any - still you are required to file a tax return.Let me know if you need any clarification of help with reporting.