Checking online I came across:

http://www.charlwoodleig...gifting%20exemption.pdf

Page 2 deals with this question:
"HMRC have confirmed to us that regular withdrawals from flexible pensions, irrespective of
the levels withdrawn and whether taken as tax free cash or taxable income, always count as
income for the purpose of the IHT exemption."

(But I would still check with HMRC).

@D Bergman
I don't see why you cannot apportion household expenses in any proportion that you choose, but (to be 'safe') you would need to be able to justify that claim in your records. I don't think there can be any reasonable challenge to a 50:50 apportionment where two people are the sole occupants of a property.

My father's income was greater than that of my mother, but as both were making Gifts from Income it didn't make any difference how the expenses were apportioned as all the 'surplus' was being gifted.

I see your point (and also Money Spider's), but how would one deal with this:

If we bought a £1M house, based on my income of £100K and my wife's £40K, should the mortgage and council tax expenses be 50:50?
Our expensive holidays are possible because of my higher income; how do we split them?

I suspect that both of you are correct and HMRC would take the view that a 50:50 split is the only one possible, but it's an interesting question.

Edit - just did some checking, and if we were to split expenditure 50:50, then as a result of differing incomes, in some years one of us would be in deficit rather than in surplus.
So would the higher-income partner need to allocate some of his surplus to clearing the other's deficit before figuring out the "true" surplus?

Opening a can of worms comes to mind!

I think that you are over-thinking this. HMRC will likely accept what is reasonable.

So if (for example) you have an income of £100k p.a. but your wife is receiving a state pension of £8k p.a. and stays at home then it would not be unreasonable for you to pay a higher proportion of the expenses, but she could not then make gifts from income of £8k p.a. and claim that she has no expenses.

In the above hypothetical scenario I wouldn't claim that your wife makes any gifts from income. She might have other investments of course which gives her 'income'. She might have capital (which you might have gifted to her, free of tax between spouses) from which to make 'annual exempt gifts'.

Write it down. Does it look reasonable? If so, then it probably is.
However, I don't think that you can go wrong with 50:50.

Disclaimer:
Delete/insert: partner/significant other, he/she as your affinity to political correctness requires. ;-)

Fair point and I can see what you are saying - though, sometimes, there could be a valid reason like paying for a deposit on first property or a big wedding gift or paying off university fee debt. (Debate about whether one should or not is a different thread!). Though, to keep the pension capital below LTA will not work, will it or am I not thinking right? As soon as you withdraw, it counts towards your % LTA and adds to the total %.