Ken

If it was the only property he owned (he said he used the money to buy a property in Australia so I'm assuming he didn't already have one) then provided he lived there within the last 6 years, it was still his main residence and so CGT exempt regardless of being rented out.

Did you live in the property at any point? You can still claim the main residence exemption for up to 6 years after you ceased to live there. You can only claim the main residence on one property at a time though, so it depends upon what other properties you own.

I think the problem might be that when you get a new passport it has a new number. The system ought to recognise the passport number if you previously had a visa on it (and if that visa was cancelled because you became a citizen it ought to know you are a citizen) but harder to catch if it's a new passport.

No. Between those dates is after the Initial Entry Date and if you wait until then you'll invalidate the visa.

That is just wishful thinking. You would still be viewed as having received the pension and taxed on it before you deposited it in the trust. You can't turn your income into trust income. You could turn an asset into a trust asset and then the income from that asset becomes trust income, but to do that you'd need to convert your entire pension fund into a trust asset which would trigger a host of tax issues in both the UK and Australia. If you have any spare cash to invest you might want to put it into accounts opened only in your wife's name as the interest/dividends paid will effectively be tax free.

She has, but the point is that thousands (perhaps tens of thousands) of other people are doing the same thing and don't have a spouse with the political exposure to force them to change.

Normally neither need to pay it back (the only exception is if you paid them too much) since only one will take tax at source. If you have an Australian employer they'll have paid PAYGW, but nothing will have gone to HMRC. If your Australian employment income is taxable in the UK it will need to be reported on a Self Assessment Tax Return. The foreign income pages of the Return (section SA106) have all the boxes necessary to report the amount of tax you have paid in Australia. Only if UK tax due is higher than the tax you paid in Australia will you have to pay any UK tax. If the UK tax is lower you will not get a refund (although if you've been taxed at source on other UK income you might get that tax refunded). It works the same when it's the other way around (e.g. if you have UK income that is taxable in Australia) however as you are on a temporary visa that does not apply to you. If split treatment applies (which is the case if you've permanently moved to Australia) then only your Australian income (and Australian tax paid) for the part of the year you were UK resident is entered on your UK tax return (but UK income for the full year). This might get you a refund of UK tax withheld back from HMRC (if you've paid too much), but there wouldn't be any Australian employment income taxed in the UK so your question about claiming tax back is irrelevant.

Absolutely everything to do with the double taxation system. The Double Taxation Agreement (DTA) between the UK and Australia specifically allocates the taxation of pension income only to the country where the pensioner is resident. This is different to the rules on all other income.

Sorry, but I can't see how one withdrawal would give you any advantage over twelve withdrawals in the same tax year (assuming you're a UK resident for the whole tax year). It's still income and if your total income is over the tax-free threshold you'll be paying tax.

I find it curious that you are concerned about spreading the investment between banks due to the FSCS threshold, yet you seem happy to leave it all in one Super fund despite a Super fund having no government guarantee at all.

Your first year back doesn't begin until you return. That approach only makes sense if HMRC's power to deem you resident was restricted to the period between the beginning of the tax year and the date you returned. It isn't. If they've got grounds to deem you resident (such as a home in the UK available for you to live in - meaning one that isn't rented out) they're not restricted to the current tax year but can apply it to any years that the grounds existed. If they don't have any grounds to deem you resident, then they can't.

But what are their exchange rates? The fee is normally a tiny fraction of what you pay.

An interim solution is an account with Wise. You can get a physical debit card (sent to your UK address) that you'll be able to use from day one (without any of the FX hassle of using a foreign card). You can even have an Australian BSB and account number if you need to give anyone Australian bank details before you arrive.

There is a strong argument to make that the amounts the grandparents paid in over the years (but not the interest/investment gains) were gifts and so exempt from tax and so you should exclude them from the amount received. The problem is that if the ATO enquire into whether or not they were gifts, you could even need to prove the source of where the grandparents got the money for the gifts to show that it really was a gift and not a disguised source of income. To do this properly you should get a Private Ruling from the ATO agreeing how much of the total received was gifts - but as you aren't looking at more that $300 of tax in total (based on the rough figures given) going to that effort would cost more than it saved.

Make a holiday of it and see all the sights to get your money's worth. Neither you nor your son will have the opportunity to visit London for a long time.