In this letter, we derived a mathematical expression that can help in developing a generalized rational sampling rate conversion polyphase finite impulse response filter, for all relatively prime values of the upsampling ( $L$) and downsampling ( $M$) factors. In contrast to the existing approaches, the proposed structure efficiently exploits the involved noncausality to eliminate input delay requirements. In addition, the minimization of output delay requirement is presented. A numerical example is also studied to validate the proposed structure. We further evaluate the performance of the proposed structure in terms of total delay requirements ($\mathcal {D}$), multiplication complexity ( $\mathcal {M}$), and addition complexity ( $\mathcal {A}$). Compared to a similar recent approach, the proposed structure is found to be more efficient in terms of $\mathcal {D}$ for $L<M$ and $L>M$. However, it has reduced computational complexity in terms of $\mathcal {A}$ than the existing approach for $L<M$ and same for $L>M$, whereas both approaches have same $\mathcal {M}$ for $L<M$ and $L>M$.