I am sorry if this has been covered before, but I have looked through the threads and not found anything relevant. If there is, then can you kindly point me in the right direction?

I have been separated from hubby for 2 years - informed community, change of address etc, but am still being charged the same as him tax-wise, which is a lot. Looks like they do half-half. He works full-time and I earn not a great deal teaching part-time.
What gives?

You're probably being taxed at the percentage that you would be if you weren't separated - meaning they combine your income and tax you both at the rate for the combined. That's what they did when my husband moved to the UK ahead of me.

You should be able to change your filing status simply by declaring it to your local tax office. I was in the same situation and did not have to produce any proof, so give it a try. They'll issue you a new tax ID number to use from now on.

As for claiming your past over-payments, if you think it's worth the cost of an accountant go for it. I did and it worked... with patience.

Check with your employer. They should be able to tell you what scale your are being taxed on. In fact, it's the employer that fills in a form and gets the notification of the correct tax scale to use, so it might be that they haven't changed your status.

Your employer can contact the tax office and get it clarified.

The other option is to spend a few hundred francs and ask a tax agent to look at it for you.

I'm assuming you are paying Quellensteuer (tax at source)...and are there children involved ? I have no idea how the 'kinderzulagen' (discount for children) are calculated for separated couples...