If interest is paid on an instalment basis, will the payer be obliged to collect withholding tax?

Some double taxation conventions indicate that, in the case of interest on instalment payments, the payer will not be subject to withholding tax. For example, pursuant to Article 11(3)(c) of the DTC between Poland and Germany, in the case of a sale on credit of industrial, commercial or scientific equipment, interest is only subject to taxation in the State in which the beneficial owner is resident or established.