I hadn't read that detail though. Are you sure this applies to Irish citizens? Our situation is a bit different from other EU countries. I'm pretty sure that I read somewhere that UK and Irish citizens can live in one country and work in the other.
Under the CTA, British and Irish citizens can move freely and reside in either jurisdiction and enjoy associated rights and privileges, including the right to work, study and vote in certain elections, as well as to access social welfare benefits and health services.
However, your wife is from Japan. Irish citizens are treated as settled upon taking up residency in the UK. That means they are treated the same way with British citizens, EU settled status and ILR persons. But, all the mentioned categories can't wake up and just bring foreign spouse to come and live in the UK. They all have to jump thru hoops, even Brits.
https://www.gov.uk/uk-family-visa/partner-spouse
Give proof of your income
You and your partner must have a combined income of at least £18,600 a year if:
you’re applying as a partner
you want to settle in the UK (get ‘indefinite leave to remain’) within 5 years
You must prove you have extra money if you have children who:
are not British or Irish citizens
do not have pre-settled status
are not permanently settled in the UK
You might not need to prove you have extra money if your children are citizens of the EU, Iceland, Liechtenstein, Norway or Switzerland and they do not have pre-settled status or are not permanently settled in the UK. Check the guidance in appendix FM 1.7: financial requirement for more information.
If you need to prove extra money for your children, you’ll need to earn an extra:
£3,800 a year for your first child
£2,400 a year for each child you have after your first child
This is called the ‘minimum income requirement’.
You may be able to use your savings instead of income.
How you prove you have the money depends on how you got the income.
If you’ve experienced a loss of income because of coronavirus (COVID-19), for example if you’ve been furloughed or you’re self employed, you might still be able to apply. Read the guidance for UK visa applicants and temporary UK residents.
What counts as income
You and your partner can use:
income from employment before tax and National Insurance (check your P60 or payslips) - you can only use your own income if you earn it in the UK
income you earn from self-employment or as a director of a limited company in the UK - check your Self Assessment tax return
cash savings above £16,000
money from a pension
non-work income, for example from property rentals or dividends
If you’re using income from self-employment or employment, you’ll need to prove you or your partner received that income for 6 months or more.
Example
You’ve worked with the same employer earning £18,600 or more for 6 months or longer.
