Are mandate contracts, contracts for specific work, or rental income accepted when applying for mortgage?

Yes. Mandate contracts, contracts for specific work, and rental income are accepted only as additional income.
Required documentation includes:

• Mandate contracts / contracts for specific work:
  Contracts from the last 6–12 months along with settlement statements, and bank statements confirming the inflows.

• Rental income:
  PSD2 access or bank account statements confirming rental inflows.