In all honesty, the best thing you can do is get a good accountant. They can help your tax position in a legal way and ensure that you pay what you should do. I don't see any comparison with huge corporations not paying tax and having a professional ensure that you only pay what you should be paying.

Taxes are no democratic and silly.
A chap could have some bits of collection and living with a minimal salary.
It s like horse racing : it’s a passion, sickness , and we give enough to the governments because of that.
And it will still be the richer to know how to avoid to pay taxes with their lawyers or backdoors.
Taxes on art are prehistoric things : art is not only Van Gogh, Soulage, or Rembrandt artworks, it could be a print of a local mate that is living because of his sales.
As read, don’t sell.
It will be an incredible increase of silly money for prints sold to USA or UK ( after Brexit ) for European !
Europe was novateur. Taxes are a trap and regression : never updates in the good sens. Germany is one of the best country about taxes : they like their people.
Only richer will could enjoy art and buy prints now : as said : anti democratic thing.

The CGT for the sale of your new piece will be sale value - market value of swapped piece at date of swap.
The CGT that might have been due for the swapped piece will be market value at time of swap - purchase price.
Market values are an inaccurate science but can be based on auction sales at the time.
I’m not an expert but that’s my understanding. Hope helps!

Thank for your responses. I had presumed as much but it's nice to have a bit of clarification.

Ah, okay... that makes sense and, if so, I stand corrected.

But couldn't one simply avoid CGT by trading with an equal value piece each year and therefore using up £25k of allowance ad infinitum.  So, conceivably, if you and I both had the same print that we bought for £200 that went up by less than £25k each year, we could simply keep trading it back and forth with each other.  After ten years we both sell our prints for £250k each yet neither of us have any CGT as we've just been utilising our (married - individually, not to each other) £25k bands each year?

Just spitballing as, like I say, I've been looking into this.

I think you have to invest the whole of the gain to qualify though, correct?

cash is king

Hmmm, I sold a car for 10k... lost about £120 in fake £20 notes when I deposited in the bank.  

sense of humour alert

If you're getting stung for thousands, you're making tens of thousands profit on your £100 bit of paper so it's not too bad.  

Not sure I agree

I don't think it right if i made say £40k profit on something I had bought years ago i'd pay less tax than a guy who had worked all year to earn £30k

(Does the maths work on above?)

I feel your pain.  And I agree with the sentiment.  But I don't think you're actually being penalised in that instance. We know when we make purchases that CGT exists and that if must be factored in to any return.  The VAT isn't really relevant in that you can count it in the cost of the original piece to offset against the gain.  And you gain £25k tax free.  And any other gain is taxed at 10% if you're a lower rate tax payer and the gain stays within this.  

So your original piece of paper cost you £125 that you had to earn before tax.  Government took the £25 tax and left you with £100 to buy the paper (forget NI for a moment)... then you pay £20 VAT on top... so it's 'cost' you £145 to buy your piece of paper.  Let's say it's now worth £50,000.  If you're married and provided your combined income is £75,000 or less, your CGT bill is £2,488.  So you get to keep £47,512.  Anybody on minimum wage might quibble this is a harsh penalty for such a windfall.

Inheritance tax... yeah... I don't disagree but I don't know as much about the ins and outs of it to comment.  That seems much more like a double whammy though in that I can earn a million pounds, get taxed at 45%, leave (broadly) the £550k to my kids and they get immediately taxed at 40% on a massive whack of that.  So in that case, there has been no gain, just a death.  Now that I feel is more unfair.

But like I say, I hear the point you make.  Just my take on it.

So do most people on here pay it or chance their luck?

Seems very difficult to enforce - a print, say, bought nearly two decades ago in cash...

Any bank transfer over 9999 is automatically reported to HMRC. Also if the buyer is an institution or gallery they may be audited and then if it’s within 7 years you’ll get a knock on the door. There are lots of legal methods to reduce tax, offshore, there are also payments in btc .. but you’ll pay tax on any profits on that too.