How to provide proof of income to the tax office

I left DE during 2005. I have no means to prove my income during 2005 - normally they would ask for payslips but I do not have them. Can anybody tell me if the "Certificate EU/EWR" will be acceptable as proof of income? Would they also need to be informed of UK non-taxable income? I assume not as payslips do not show non-taxable income only taxble. As anybody any idea on this one?

Could you not try and get copies of your payslips from your old company?

From what I've been told the Krankenkassen can issue some kind of a statement for that kind of thing. You might want to ask there.

If you have nothing else you could show them bank statements - I assume you want to avoid doing this. Did you get paid by an employer during this time (payslips?) or were you freelancing (invoices?).

At the end of the year (or on termination of your employment) your employer should have provided you with evidence of earnings and tax paid in the form of a "Lohnsteuerbescheinigung". They will also have transferred this information electronically to the Tax authorities (a requirement since 2005), so the tax man should already know the details. You can also request your ex-employer to provide a replacement copy of this certificate, but they can make a small charge for the effort to provide it. They are themselves required to retain this data easilly to hand for at least 10 years.

I never heard of a "Certificate EU/EUR"

You are supposed to advise the German taxman of your global income during the tax year affected, but then it starts to get complicated, as you would also have to show evidence of any tax already applied elsewhere so you are not double taxed. I'd be inclined to simply show them your German earinings (which are their main interest) and hope they don't ask further questions. A visit to a Steuerberater is strongly advised, if only to get information on the tax benefits that may be due to you as a result of your moving out of Germany. It's highly likely that the German taxman owes you money.