In Germany tax laws might help you a little bit with this.
If you build something with the main interest of making money out of it, the state (and most probably your employer) will treat it as a business and want you to run a business for that or will likely forbid to do it. But if you build something because you need it for yourself and are running it more like a hobby but make profits from it, there´s something called "Liebhaberei". This special status mainly has tax implications (you can´t get refunds on losses from your Liebhaberei because it´s not qualified as a business, tax-wise...) but I´ve had friends which got their side projects "approved" by their employers because they did not look like real businesses and were run on this Liebhaberei status.
So if you like miniature railways and build a niche site around it, which will give you beer money (or a bit more), the tax people most probably won´t have any problems with that. You should avoid doing things that look like you are running a business (having a shop, selling stuff), but most of them probably won´t even notice affiliate links or understand what that does.
This can also help you with your employer. "Boss, I have this site about my miniature railways and now it´s making 50 bucks a month, is that a problem?"
Or you go the right way. Be honest and say that you´d like to do something for fun but there could be money involved and you just wanted to make sure that´s okay for everybody. I found employers to be unexpectedly tolerant when you´re honest.
If you build something with the main interest of making money out of it, the state (and most probably your employer) will treat it as a business and want you to run a business for that or will likely forbid to do it. But if you build something because you need it for yourself and are running it more like a hobby but make profits from it, there´s something called "Liebhaberei". This special status mainly has tax implications (you can´t get refunds on losses from your Liebhaberei because it´s not qualified as a business, tax-wise...) but I´ve had friends which got their side projects "approved" by their employers because they did not look like real businesses and were run on this Liebhaberei status.
So if you like miniature railways and build a niche site around it, which will give you beer money (or a bit more), the tax people most probably won´t have any problems with that. You should avoid doing things that look like you are running a business (having a shop, selling stuff), but most of them probably won´t even notice affiliate links or understand what that does.
This can also help you with your employer. "Boss, I have this site about my miniature railways and now it´s making 50 bucks a month, is that a problem?"
Or you go the right way. Be honest and say that you´d like to do something for fun but there could be money involved and you just wanted to make sure that´s okay for everybody. I found employers to be unexpectedly tolerant when you´re honest.