Scalable Video Coding (SVC) is the finalized standard as an extension of H.264/AVC to provide stable multimedia services to various service environment and end-systems. Usually an exhaustive block mode search has been employed to determine the best coding mode for each Macroblock (MB). This gives a high coding efficiency, however it causes very high computational complexity in encoding system. To reduce this complexity of the exhaustive mode search, researchers propose a fast mode determination algorithm for inter-frame coding based on correlative information between base layer and enhancement layers for providing spatial scalability with Medium Grain Signal to noise ratio (MGS) layer. In the proposed algorithm, researchers use Rate-Distortion (RD) costs of BLS (Base Layer Skip) and 16x16 modes and mode information of a corresponding block of the base layer to finish inter-mode search procedure early in the neighboring enhancement layer. Also, an adaptive thresholding scheme is designed. Researchers verify that the overall encoding time can be reduced up to 66.5% based on comparative analysis of experimental results with JSVM 9.12 reference software.