What cannot be deducted as maintenance payments to ex-spouses?

Of course, not all payments to your ex-spouse can be claimed as special expenses. This includes gifts you give your ex-partner on special occasions (birthday, Christmas, etc.). Child maintenance is also not deductible.

This should be covered by child benefit or child allowances. Payments and benefits resulting from equalisation of accrued gains are also not deductible (e.g. taking over a car). The same applies to legal and court costs incurred to obtain your ex-spouse's consent to income splitting.