Try overlap deliberately
With a longer skirt, the hem may fall over the boot shaft. It needs enough width and a surface that does not continually catch on the footwear. Walk and turn. A small slit or pleat can respond differently at a shaft edge from the rest of the skirt.
When both edges sit at similar heights, they may alternately cover one another during movement. You may enjoy that effect, but it should not create uncomfortable bunches. Compare a slightly shorter or longer skirt if correction is repeatedly needed.
Leave a visible gap
A shorter skirt reveals more leg or tights between hem and boot. Choose the visible layer for your preferred coverage and comfort. A colour similar to the shoe connects the areas; contrast separates them more clearly. Neither option is automatically correct for a particular height.
Sit down and inspect the gap again. The skirt moves, and the upper shaft edge can sit differently while seated. Check whether it presses or pushes awkwardly behind the knee. The combination needs to remain as wearable in that position as while standing.
Judge shaft width beyond appearance
A boot should close normally and allow the intended movements. Do not insert a thick extra layer solely to show a certain colour if it compromises fit. Another tights model or another boot may work better.
With a wide shaft, the skirt may slip inside or catch on a tab. Observe this with the specific pair. A description such as riding boot or tall boot does not describe every edge relevant to the combination.
Test the coat last
The coat introduces another hem height. You do not need to align all three lines exactly. Instead, inspect the areas together and check that you can walk comfortably with the coat fastened. A plain upper combination is enough for the first comparison.
When you find a successful version, record skirt, boots and tights together. Another shaft design can change the behaviour even when its colour is identical. The exact combination is therefore more valuable than a blanket recommendation about which skirt length supposedly always suits tall boots.
