I’m a freelancer but send invoices through a LTD. I have a verification letter of employment from the company I work with including the name of my LTD. The invoices have my name on it also. I have certificates of incorporation ect.
However I could change it and the verification letter could have just my name in it but I bill them through my Ltd which I also use for my e commerce website and some other things.
You should look up double tax treaties/agreements. Many cases if you already paid taxes over your income in for example the source country or residence country you can’t be taxed again.
because I needed to show the funds. 500k my father been living in Thailand for 12 years. I have letter of employment and can work remotely. Also my own company ect.