Good evening,

Can I please outline a scenario and invite informed feedback...

I'm a UK national currently resident in the UK and working freelance for UK based clients. I'm married to a German national who is currently resident in the UK and we have two young children.

We would like to move to Germany and I will continue to work freelance for my UK clients.

From my research so far:

There is a double taxation treaty between the UK & De (Germany), which essentially says that UK income would be taxed in the UK and any De income would be taxed in De.

Tax returns in both UK & De would be required, 
For the De tax return, all world wide income needs to be declared but it doesn’t get taxed, Your complete world wide income is used to calculate the rate of tax you will pay in De on your De income... Now what I haven’t determined yet from my research is how this effects the personal allowance for a De tax return? Do I still retain my full tax free allowance on De income or does the foreign income reduce the allowance on my De income? Other factors to note are the option to combine a married couples allowance in De, this would be an attractive option should I start working for De clients. Also the other way around, If  I was to earn Income in De, would this reduce my tax free allowance in the UK?
Social Security is the next tricky detail to sort...
I believe the definition that would define me is ‘EU cross boarder commuter’
From my research, if the bulk (>75%) of my work/income/activity.. is UK based then I will continue to pay UK NIC’s (National Insurance Contributions) and the UK will be responsible for my Social Security benefits regardless of where I’m resident (in the EU)... And I will be exempt from the mandatory De Social Security.... So health care in De would be funded via my UK NIC’s?? I would need to get A1/S1 forms from the UK DWP...??
So basically I will be commuting back from Germany to The UK to work for my UK clients, I will continue to pay UK NIC’s. What I’m not confident on is will I still have access to UK funded health care while I’m resident in Germany? Will the UK fund my health care through the De health care providers?.... Sounds too good to be true?
Now for my scenario is there any time limit on this arrangement for Social Security, I’ve seen mentioned a 2yr limit for workers posted overseas by their UK employer... But since I don’t intend to work in Germany or at most 25% of my activity will be based in Germany.... then there is no time limit to this arrangement?
I also need to establish the benefit options for my Wife and Children under this arrangement, remembering that my Wife is actually a German national....
Of course I am very much keeping my head in the sand regarding all this when it comes to Brexit...! I firmly intend to just deal with it when it does.... or Doesn’t

Regards

Oliver