我目前在英国，已经工作两年，来英国之前在日本生活+工作两年，我很喜欢在日本的生
活，所以将来预计要回日本长住，目前的公司在日本有分部，若我决定回日本公司也会帮
我处理签证相关事项。
我目前正在犹豫是否要提前回日本，或是拿到英国公民后再回日本。如果要拿公民再回日
本我估计还需要至少四年半 (再三年拿永居，永居满一年申请公民，拿到公民申请护照，
再请公司办日本签证然后等签证下来，然后回日本，假如一切顺利的话）。
想请问大家有什么看法？谢谢！
== 更新 1207 ==
Tax if you leave the UK to live abroad
https://www.gov.uk/tax-right-retire-abroad-return-to-uk
如果不再是英国居民：海外所得免缴税，如果有英国的收入，例如房租才要缴。
变成不是英国居民的条件(either)：
1. you spent fewer than 16 days in the UK (or 46 days if you have not been
classed as UK resident for the 3 previous tax years)
2. you work abroad full-time (averaging at least 35 hours a week) and spent
fewer than 91 days in the UK, of which no more than 30 were spent working
National Insurance:
1. You might be able to pay National Insurance while you’re abroad if you’re
planning to:
* come back to the UK
* claim the State Pension later
2. You cannot claim back any National Insurance you’ve paid in the UK if you
leave the UK permanently. However, anything you’ve paid might count towards
benefits in the country you’re moving to - if it’s one of the countries
that have a social security agreement with the UK.
https://www.gov.uk/government/publications/reciprocal-agreements/reciprocal-agreements
(Chile, Japan and South Korea only cover social security contribution
liability and do not include benefits. These are known as Double Contribution
Conventions.)
另外如果决定移居海外或在海外退休，需要在英国端跑一些程序：
https://www.gov.uk/moving-or-retiring-abroad
目前我还是没办法决定要暂时留英或是明年回日...:(