no one wants to talk about the EU taxes they would be paying
Hey, I'll talk taxes! Don't want to disappoint! My brother worked as a boxing and MMA trainer in England a few months a year for about five years. Taxes go something like this:
Most of the time, non-UK residents temporarily visiting the UK to carry out work duties do not incur a UK tax charge, whether they are employed or self-employed. If a UK tax liability were to arise, the non-resident will usually find protection by virtue of being able to offset all or some of that charge in accordance with the terms of a tax treaty to prevent ‘double taxation’ – that is, being taxed twice on the same income, by different jurisdictional authorities. However, this protection does not extend to non-UK resident sportspeople who are taxable in the UK when performing or training here.
If a sportsperson or entertainer’s gross annual payment exceeds the personal allowance, around $17,000, any individual or organisation that pays that person is required to withhold basic rate income tax. It’s likely that additional UK tax will be due if the individual’s net profit exceeds the personal allowance and basic rate band in a tax year, around $67,000. In that case, the performer is required to register for self-assessment and file a UK tax return and will be exposed to UK income tax at the usual rates (20% basic rate, 40% higher rate and the additional 45% on income over $175,000 (approx) after expense deductions.
Allowable expenses such as travel, accommodation, coaching etc. could produce a reimbursement of some or the entirety of the 20% withholding tax. This cashflow disadvantage can be alleviated or eliminated by submitting an application to Great Britain's foreign entertainers’ unit, requesting that tax be assessed based on the expected net profit, rather than the gross appearance fee. In most jurisdictions, tax is applied to income directly associated with the appearance fee or prize money received. However, the UK stands out as one of the few countries where an additional tax is imposed on a segment of an individual’s global endorsement income linked to their performances.
To my knowledge, only actual players and coaches are taxed as entertainers. Everyone else associated with the team on the field doesn't have to worry about this complex tax structure.
Side note: I don't know how taxes are set up in Germany.
Second side note: I'm sure the NFL would figure out an easy way you handle the taxation issue.