Do I have to register a grandchild's trust fund

xylophone

(With the adult grandchildren's money they can just hand it over -

As I commented in my post above

https://forums.moneysavingexpert.com/discussion/comment/79407417/#Comment_79407417

The two eighteen year olds may take control of their accounts.

Dumping the younger grandchildren's money in cash

I was not suggesting that the money should be "dumped"!!!

I was simply suggesting a possible solution that the OP might consider, (using Junior stocks and shares isa combined with best available child savings account until all could be invested) not that it was the optimal solution!

If the markets went up between encashment 

But then again, they might equally well go down.......that's markets for you!

And as you note. I did draw the OP's attention as to how he might negotiate the Government Gateway, with the help of HMRC if required.

xylophone

I won't go so far as to say that it breaches the duties of a trustee,

As you point out, in this particular case the money was provided by the living OP as an absolute gift to his grandchildren to be held by him as their Trustee.

As a Trustee, it is his duty to act in the best interests of the beneficiaries.

Although it is true that the solution suggested as one possibility would remove the  administrative burden on him, it seems to me that he could make a case for it ultimately to be a better solution for the beneficiaries in so far as it would move the money to a tax optimised environment which could continue after their eighteenth birthdays  -  this could  be advantageous to them in the future.

BareTrusts

I thank everyone for their responses but it seems nobody understands my situation. I even wrote to the tax office and they replied saying I should contact them on their helpline so that they could deal with my query more quickly.. Telephone number 03001231072.
I tried ringing this number today and after inputting answers to some automated questions their reply was thank you for calling good bye. With phone automatically disconnected.
HMRC are not exactly very helpful. The only comment on their automated blurb was that if I had tried to find out if I should register a trust then I would not be penalised. So I guess now I just do nothing and see if I get contacted in the future.

xylophone

https://forums.moneysavingexpert.com/discussion/6378795/do-i-have-to-register-a-grandchilds-trust-fund/p1

I thank everyone for their responses but it seems nobody understands my situation.

Did you have a look at the video in my post above?

And Malthusian's comment

 https://forums.moneysavingexpert.com/discussion/6378795/do-i-have-to-register-a-grandchilds-trust-fund/p1

Xylophone is correct - you need to register the bare trust as an "organisation". Bare trusts do not officially have names in the way that more formal trusts with trust deeds do, so something like "The John Smith Bare Trust" would do.
You will need the date the trust was established (when you made the first gift), the names of the trustees (just you), the settlor (you again), the beneficiary (the grandchild) and details of the assets in the trust (which you can get from HL). This needs to be done separately for each bare trust / grandchild.

Malthusian

I thank everyone for their responses but it seems nobody understands my situation.

Respectfully, I disagree. Your situation is that you are struggling to comply with the legal duty of a trustee to register the trust. Unfortunately, you are still struggling even after receiving detailed help from a forum (including identifying the roadblock - the fact that you weren't aware that the "register as an organisation" option is actually the correct one). There is nothing wrong with that. 
The next step is to either pay for professional help (pay a solicitor to do the registration, which can come out of the bare trusts' money) or find someone who can help you unofficially for free (e.g. a relative who can navigate the Government Gateway).

The only comment on their automated blurb was that if I had tried to find out if I should register a trust then I would not be penalised.

I sat through the blurb myself because that would be very surprising, and that's not quite what it says.

It says that you will only be penalised for deliberate failure to register a trust, and that if you take all reasonable steps to determine whether a trust should be registered, and mistakenly decide that it isn't, no penalty would be applied at that point. You would however get a warning letter from HMRC in due course and then have to register to avoid a potential £5,000 penalty.

Your bare trusts are very definitely required to register (it's open-and-shut), and you now know that. However, HMRC's stated policy (see link above) is that you will get away with doing nothing for as long as they haven't sent you a warning letter yet. The fact that your failure is actually deliberate should in theory not result in a penalty, as long as you act on the warning letters if/when they come.

HMRC says:
Where failures to register are due to deliberate behaviour on the part of the trustees, a £5000 penalty may be charged per offence.
In practice this means that should HMRC become aware of a trust which has not been registered by the relevant deadline – either because that trust has been registered late or because HMRC have identified that trust’s existence by other means – HMRC may issue a warning letter to the trustee or agent. If the trust is not yet registered, the trustee or agent should register it at that point. If the trustee or agent then fails to register the trust within the time period stated within the warning letter, or fails to explain why their trust is not liable to registration, a penalty may be issued to the lead trustee.

Personally I can't see any reason to worry about whether or when they will send you a letter. Rather than go to a solicitor or someone else who can just get the job done. 

It is the grandchildren's money, you have already been very generous by giving them the money in the first place, they can pay the solicitor's fee (where it's not practical to save them the fee by DIYing).