Mark attendance in your monthly sheet as you already do. This reads it every time you open the page and tells you who is in, who is out, and what today costs — so month-end is a review instead of a reconstruction.
The tab you mark in is a working sheet — it gets renamed, overwritten, or the next month is typed over it. Filing puts the month into your workbook as Attendance_YYYY-MM, alongside every other month and the payroll runs, so June is still readable in December. The marks themselves are filed, not just the totals, because a day-by-day register is what an inspector asks to see.
One tab per month, named for the month — August 2026, Aug-2026 or 08-2026 all work. Employee names down the left exactly as they appear in your Employee Master, and the days of the month across the top. Write the mark in the cell; for overtime, add a plus and the hours — P+2 is present with two hours overtime.