After a sleepless night and endless questioning in my head, I would be grateful if people could point me in the right direction here. I am a sole practitioner who has just taken on a number of clients, all of which have at least one non-resident director / employee who perform duties outside of the UK who have at sometime had business travel expenses paid for by the company. From a UK tax perspective I am in a conundrum regarding whether to complete a P11D or not. None of these companies are PAYE registered as they don't have any UK payroll, the directors / employees in question do not have an NI number and I am happy that any travel expenditure has been for business purposes and that there will be no UK tax / NI consequences (on the basis that expenditure is for business purposes and the fact that the directors / employees in question are not resident in the UK). The prospect of registering for payroll, getting NI numbers etc just seems to be completely over the top given that in practise some people just wouldn't bother with a P11D in this instance. But I don't want to run the risk of clients getting fines later down the road. My head tells me the right thing to do is to submit a P11D, however is there an easy way to do this without a PAYE reference and an NI number - I have seen people saying that the CT reference number can be used but does this work in practise? And what should I use for the NI number? Or should I just not bother? Any advice greatly appreciated.