It is up to the Ph.D. candidate to arrange a gathering. In that case, the candidate has to cover the expenses.
The expenses can be deducted from the tax. Deductions in connection with a Ph.D. are in addition to the minimum standard deduction. The deduction has to be entered under item 3.3.7, and the candidate must be able to document the deduction with receipts and present a list of the participants’ names if asked to do so by the tax office. A deduction will only be given for the dinner for supervisors, opponents, etc., and not for food expenses relating to family and friends.