In March 2026 the son-eomneun days fall on 7, 8, 17, 18, 27, 28. 6 in all. These are days whose lunar date ends in 9 or 0 — long the first thing people check before moving house or opening a shop.
March 1: 삼일절; March 2: 대체공휴일(삼일절). Taken from Korea Astronomy and Space Science Institute open data.
March 5: 경칩; March 20: 춘분. Computed from the sun's ecliptic longitude, not looked up in a table.
These dates hold for every visitor. A son-eomneun day is fixed by the lunar calendar alone and has nothing to do with your birth chart. What a given day means for you needs a birth date — there is no auspicious day that holds for everybody.