<p>Fitting SO<sub>2</sub> dSCDs from MAX-DOAS measurements of scattered sunlight is challenging because actinic light intensity is low in wavelength regions where the SO<sub>2</sub> absorption features are strongest. SO<sub>2</sub> dSCDs were fit with different wavelength windows (λ<sub>low</sub> to λ<sub>high</sub>) from ambient measurements with calibration cells of 2.2 × 1017 and 2.2 × 1016 molec cm<sup>−2</sup> inserted in the light path at different viewing elevation angles. SO<sub>2</sub> dSCDs were the least accurate and fit errors were the largest for fitting windows with λ<sub>low</sub> < 307 nm or λ<sub>low</sub> > 312 nm. The SO<sub>2</sub> dSCDs also exhibited an inverse relationship with the SO<sub>2</sub> absorption cross-section for fitting windows with λ<sub>low</sub> < 307 nm. Spectra measured at low viewing elevation angles (i.e., α = 2<sup>o</sup>) exhibited less accurate SO<sub>2</sub> dSCDs for the same fitting windows compared to higher angles. The use of a 400 nm short-pass filter or a polynomial to account for stray light (the offset function), increased the accuracy of the SO<sub>2</sub> dSCDs for many different fitting windows, decreased fit errors, and decreased the dSCDs’ dependence on the SO<sub>2</sub> absorption features. The inaccuracies at lower fitting wavelengths were increased by stray light originating from light with λ > 400 nm. Deviation of the SO<sub>2</sub> dSCD from the true value depended on the SO<sub>2</sub> concentration for some fitting windows rather than exhibiting a consistent bias. Uncertainties of the SO<sub>2</sub> dSCD reported by the fit algorithm were significantly less than the true error for many windows, particularly for the measurements without the filter or offset function. For retrievals with the filter or offset function, increasing λ<sub>high</sub> > 320 nm tended to decrease the reported fit uncertainty but did not increase the accuracy. Based on the results of this study, a short-pass filter and a fitting window of 307.5 < λ < 319 nm are recommended. If a filter is not available or conflicts with other species to be determined (NO<sub>2</sub>, HCHO, etc.), the offset function should be enabled, and a fit window 307.5 < λ < 319 nm is still recommended.</p>