Your situation is quite similar to mine and that of a few other people. There are previous threads discussing most of what you’re asking about, so you might want to check those out. A couple of examples (you’ll probably find additional ones by searching for “freelance”, “freelancing”, etc.):
Most of what you wrote sounded mostly fine to me. Some responses to some of your specific questions below.
I think you’d make things easier for yourself if you started sending bilingual invoices (German followed by English translations for each field) from this point on. I think I might have submitted one or two things to the tax office in German at some point and I suspect they’d be able to figure out an invoice entirely written in German, but I don’t think it’d hurt if you included English translations as well and you might save yourself some potential hassle later. And I’m guessing you need to keep the first language as German for your German clients.
You don’t need to write the amount in TWD or the exchange rate. It doesn’t matter. When the time comes to file taxes, you’ll enter your total annual income for each client in EUR and the tax software will convert it into TWD using the exchange rate for December from the National Taxation Bureau.
Nope, you don’t need to, AFAIK (also discussed previously), and you don’t need to register as a freelancer as in Germany. I think you’re fine to just start working and writing invoices. That’s what I’ve done the last few years anyway.
Yes, that’s fine. The tax year is the same as the calendar year, and taxes need to be filed in May (or June for the last couple of years, because of COVID). From what you’ve written, it doesn’t seem like you’ll need to worry about this until May 2024 (for your 2023 income).
There are no strict requirements for invoices in Taiwan as far as I’m aware - I think that anything you’ve already been sending to Germany will also be fine here. Since you’re invoicing German clients though, they’ll probably still expect the invoices to be written with all the usual information required in Germany, and there would be little reason for you to start omitting unique invoice numbers, dates, addresses, and so on.
There might be additional bits you should still include to make things simpler on the German end, like “recipient is not liable for VAT”/“Steuerschuldnerschaft des Leistungsempfängers” and your ARC number in place of a Steuernummer. I’m just going from my old invoices there - I don’t know the current rules for invoicing Germany from outside Germany.
Nope, it’s fine AFAIK. You’d presumably intend to have additional clients after the first few months anyway, but even if you didn’t I think it’s fine.
They’re only applicable if you earn over NT$3 million in a year. Otherwise, you’re paying the same tax rate as everyone else. Assuming you’re single with no dependents, your income tax on an annual income of NT$800k in 2022 would be around NT$18,850 per year (it’s 5% of NT$800k minus NT$423k, which is the sum of all the basic exemptions and deductions). If you have dependents or additional deductions it’ll be lower. I imagine that’s quite a bit lower than in Germany, so welcome to a low-tax country.
Plus NT$826 per month for National Health Insurance, when you get it.
Yeah, there are, but I’m getting bored of typing. The government one, findable via Google, doesn’t seem to have been updated for the 2022 allowances yet. Tax in Taiwan is pretty simple though, especially compared to Germany.
I’m not sure. I had to wait 6 months, but then there was some discussion that gold card holders may be eligible immediately, then I remember reading it hadn’t really worked out like this and that only applied to those working for Taiwanese companies. There are probably threads about it though.
NT$826 if you don’t have local income. This is one of the rare occasions that the Taiwanese government never thinking about foreigners when they do stuff has worked in our favor.
No, I don’t think so. Not unless you start a company or something. For routine, relatively cheap stuff like computer equipment, I don’t think this would work out in your favor. The standard deductions are already quite generous.