我目前在英國，已經工作兩年，來英國之前在日本生活+工作兩年，我很喜歡在日本的生
活，所以將來預計要回日本長住，目前的公司在日本有分部，若我決定回日本公司也會幫
我處理簽證相關事項。
我目前正在猶豫是否要提前回日本，或是拿到英國公民後再回日本。如果要拿公民再回日
本我估計還需要至少四年半 (再三年拿永居，永居滿一年申請公民，拿到公民申請護照，
再請公司辦日本簽證然後等簽證下來，然後回日本，假如一切順利的話）。
想請問大家有什麼看法？謝謝！
== 更新 1207 ==
Tax if you leave the UK to live abroad
https://www.gov.uk/tax-right-retire-abroad-return-to-uk
如果不再是英國居民：海外所得免繳稅，如果有英國的收入，例如房租才要繳。
變成不是英國居民的條件(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.)
另外如果決定移居海外或在海外退休，需要在英國端跑一些程序：
https://www.gov.uk/moving-or-retiring-abroad
目前我還是沒辦法決定要暫時留英或是明年回日...:(