Here is the promised article on the refund of withholding tax on Norwegian shares. The first part deals with the preparations and the registration with the Norwegian tax authorities, the second part contains the completion of the online form.

As a placeholder times $EQNR (+0.22%) , $HAUTO (+2.15%) , $VAR (+1.36%) , $MPCC (+1.7%) , $TEL (-0.98%) , $AKRBP (+2.64%) , $TOM (-1.76%) exemplary.
Edit: This only applies to tax residents in Germany. Please enquire in Switzerland, Austria or elsewhere in Europe about the regulations that apply there. Many thanks to @GeldGenie who has created a corresponding article for Switzerland, which I am linking here: Quellentsteuer Schweiz
Norway has strong companies with some extremely attractive dividend payouts. However, some people are not aware that these dividends are subject to Norwegian withholding tax without any offsetting. This means that in addition to the 25% Norwegian withholding tax, the custodian bank also pays the capital gains tax plus solidarity surcharge and, if applicable, church tax, which means that less than half of the dividend is credited.
Don't worry, the money is not gone, it just belongs to someone else for the time being. Norway refunds 10% withholding tax on application. This can be done easily and online and can also be done retroactively for several years, for a maximum of 5 years. You can get the remaining 15% from the German tax authorities via your income tax return. A few more tips at the end.
First collect all dividend vouchers showing the withholding tax deduction. Most companies pay out quarterly, so there should be 4 receipts per calendar year. You will need these in pdf format. If you are applying for a refund for several years and have more than one share in your portfolio, here is an important note: You can submit a maximum of 10 PDFs of 50 MB each attached. I will then combine the individual receipts per share into one PDF.
Apply for the tax residence certificate at your local tax office. You can find the form at: https://www.formulare-bfinv.de/ffw
Enter form 034450 in the search. You can fill out the form in your browser and then save it as a PDF and print it out. Important! Send it signed in duplicate to the office. A short cover letter with the subject "Application for a tax residence certificate for the purpose of reimbursement of overpaid withholding tax in Norway" and a short two-liner are helpful. I usually receive a confirmation copy back after 1 to max. 2 weeks. Scan and save as PDF.
Then you can already register in Norway. Under the following link Bei Altinn anmelden you can create a new user. The site is only available in the national language or in English. I use English and have activated the automatic website translation via Google, then it even works in German ;-) For the first registration, logically create a new user. Username, email, password and the security question and continue.
When you receive confirmation that a new account has been created for you, click on done and that's it with the preparations.
You will receive a 10% withholding tax refund via this process. More is not possible, even if it is described differently in various forums. You can tick the maximum refund in the form, but an error message always appears before you submit the form. So simply get 10% tax back quickly and easily and then the rest via the German tax office. If you have submitted the application in Norway quite early in the year, the refund amount should be certified by the submission deadline in Germany. Otherwise, simply take the difference (25% - 10% potential refund = 15% withholding tax on your total dividends) and enter this amount, or add it to any other amounts applied for. In the first step, tax declarations are made paperless anyway, so you can relax and have the receipt from Norway until any queries arise. However, I see difficulties with the German FA recognizing this retroactively. I therefore handle it a little more elaborately and actually have the withholding tax refunded annually and the rest via the income tax return at the same time.
If you have never done the refund in Norway before, then at least get the 10% back for the last few years and the 15% for 2024 via the KAP annex. Depending on the amount, you decide which way you want to go.
If you have any questions, please leave them in the comments and I will try to answer them as soon as possible.
Part 2 will follow in a few days with details on the form and further tips.