Okay is the gain from purchase price to sale (how much you paid) and how much you sell it for greater than £12,300?
(disclaimer, not a lawyer or accountant)
No, because it doesn't seem to be an approved scheme the gain (if applicable) is essentially from the market value on the day he makes the purchase, income tax and NI is due on the difference between the price he pays (the exercise price) and the market value, not CGT. so any CGT is only applicable beyond the amount on which he pays income and NI on - ergo exercising and selling immediately or shortly after should basically result in no or tiny GCT.
Thanks folks.
I'm not sure what the UK equivalent is to be honest as it differs from a share save scheme. It's an employee share purchase plan (US based company) that runs over 6 month periods. You put in a percentage of your salary and at the end of the 6 months you will (no choice) buy the stock at a discounted price. You pay income tax/NI contributions on the gain so this is why I'm keen to understand how you avoid CGT (and reporting) by selling as quickly as possible.
I guess the whole point is moot if the disposal proceeds are over ~£50K as I believe it would need to be reported even if there is no gain.
(disclaimer, not a lawyer or accountant)
So it sounds like a share option scheme that isn't in an HMRC-approved scheme. You mention being able to buy at a discounted price - I presume you're referring to a price that is set in advance and on a particular date? i.e. if you opt into this thing you're granted an option (the obligation to buy bit is a bit funny mind - so I am a bit unsure here)
The below is written under the assumption we're talking about some employee share option scheme.
This isn't advice but AFAIK, the basics of how options are taxed in the UK are:
Ordinary investor:
You purchase options on an exchange (paying the premium for them), if you sell the options then you make a gain or loss for CGT purposes (or indeed if they expire worthless) as these things have value themselves (the premium). If you exercise the options then the cost of the resulting shares are bundled together with the option premium for GCT purposes and there is no gain or loss until you sell the shares.
Employee in an HMRC approved scheme, for example, save as you earn scheme:
You're granted options by your employer, any notional premium is ignored even though you've just "earned" a thing of value, if they expire worthless then there is no GCT loss. You save in some savings account until expiry of the options (minor tax break on the interest here, realistically rates are low so meh). Upon expiry, you can choose to exercise the options if profitable to do so (using the savings from the special savings account), your cost for GCT purposes is based on the strike price/cost of the shares (similar to how an ordinary investor is treated), so you're (potentially) liable for GCT for the difference between that and the price you(eventually) sell at. (can be avoided by dumping into an ISA or pension). They like to say that you're getting to avoid income tax and NI via these schemes but you're (potentially) liable instead for CGT and they're basically treating you similarly to an ordinary investor (albeit ignoring any value/premium for the options you were granted).
Employee not in an HMRC approved scheme.
(This is the one that annoys me a bit in how they treat it and what I think you're referring to).
You're granted options by your employer, any notional premium for these options is ignored (as per above re: the approved schemes too). Upon expiry, you buy the shares (apparently you're forced to under your particular scheme, an option is generally the right but
not the obligation to buy an underlying asset, but meh)
Apparently this is because of the risk of tax avoidance schemes but how HMRC now treats you is rather ****ty (IMHO). You're liable for income tax and NI (not CGT!!!)on the difference between the exercise price and the value of the shares at expiry - this is naff because if you want to hold onto the shares then, unlike an ordinary investor, your tax liability (which would otherwise be CGT) isn't deferred until the sale of the shares but is charged on an (as of yet) unrealised gain(!!!), you owe income tax and NI which must be paid via self-assessment that year even if you wish to hold onto the shares (this might strongly incentivise employees to sell in order to pay that tax bill).
Your cost for CGT purposes, unlike in the HMRC approved schemes or in the case for an ordinary investor, is not the exercise price (+ premium, if applicable) but rather the value of the shares at expiry (so you're liable for CGT beyond the amount which you owe income and NI on). If you do keep them then you have a potential gain or loss for CGT purposes from that point onwards - so in theory you could later make a loss having already been taxed (income and NI) on an unrealsied gain. IMO this is unfair but meh...
disclaimer - not a lawyer/accountant The above is not advice, just a (possibly wrong) outline to the best of my knowledge that might help and some opinionated commentary, best to phone up and check etc.. 
