The background induced by misidentification of a jet as a photon is usually estimated using two-dimensional sideband method (ABCD-method). This report is devoted to an alternative method of the estimation based on maximum likelihood method using RooFit toolkit. This method doesn't require optimisation of ABCD regions definition, which results in much faster estimation. One of the main advantages of the developed method is that it takes into account data, signal and all other backgrounds distributions, which allow better estimation accuracy. The estimates of the considered method are confirmed by standard ABCD-method.