Spin-cast films of the ferroelectric copolymer poly(vinylidene fluoride-trifluoroethylene) are attractive for various applications. For such films the question arises whether there exists a ferroelectric functionality depending on film thickness. We characterize the ferroelectric properties of ultrathin films down to a layer thickness of 10 nm with spectroscopic and electrical methods (capacitance-voltage). The measurements indicate an extrinsic switching mechanism with a much lower operation voltage than that for a collective intrinsic switching. Both independent methods agree that there is no critical thickness for spin-coated copolymer films down to 10 nm if an adapted system of electrodes is used.