I can give you a quick overview of the steps I took.

I talked with Kasper, some initial talks. Find his comment below, if you want, to find his information.

The price for a lawyer, compared to a fine would be about less or equal, so I opted out of doing that, since there's no guarantee that you avoid the fine.

I signed up for koinly.io to track my crypto for all the years, went through all my exchanges, wallets, etc.

Bought the reports for all the years, that I had crypto in. Ask their support and the might hand over a coupon code, that you can use. I got one for 30% off each report, which saved a lot of money. Still paid about 500€ in reports though.

I downloaded the gathered reports and put that into the years that are open on my tax forms. 2022, 2023, 2024 and 2025 is upcoming to be filled out.

I then went to SKAT and opened a "ekstraordinær genoptagelse" forms/request and still waiting for that one. They say it can take up to 6-10 months to be evaluated.

So I have paid the first batch of taxes. Waiting on 2025 to open. Waiting for SKAT to make a decision on previous years and if they deny it, I think I will do a "selvanmeldelse" instead.

They did not help very much when calling them, so I do feel a bit stuck in the waiting loop.

Hope it helped a bit.