Yes, a large part of the Sealup range is cut to work cleanly over tailoring. Mid-length and longer coats usually allow enough room through the shoulders and body to layer over a blazer without distorting the line. If you plan to wear it primarily over suiting, consider your usual blazer size and look for fit notes about tailored layering. You may prefer your regular size for a precise look or one size up for more comfort and movement.