Factories and service firms running payroll on ERPNext keep hitting the same wall at month-end: attendance and Employee Checkin records capture when people clocked in and out, but nobody actually gets paid overtime from them automatically. ERPNext core has Timesheet and Additional Salary DocTypes, and the payroll engine will read salary components, but there is no native bridge that reads a day's check-in pairs, subtracts the standard shift, applies a weekday-vs-holiday multiplier, and produces an auditable OT figure. So teams fall back to spreadsheets — HR keys overtime hours by hand, supervisors argue over what counts as a holiday, and the numbers that hit the salary slip are impossible to trace back to the clock. On a 200-person factory floor that is both a payroll-accuracy risk and hours of avoidable admin every cycle.

We build a dedicated Frappe app (its own module, installed onto your bench) that closes that gap. A scheduler event and a hooks.py doc event on Employee Checkin/Attendance roll each employee's daily punches into worked hours, compare them against the assigned Shift Type and the standard working window, and split the excess into overtime buckets. A configurable rule engine — driven by a custom Overtime Rule DocType plus the ERPNext Holiday List and each employee's weekly-off — decides the multiplier: 1.5x for weekday overtime and 2.0x for work on holidays and rest days, with your own thresholds, rounding, and daily/weekly caps. Each computation is written to a custom Overtime Slip DocType and, where you want it, an auto-generated Timesheet with the right Activity Type and costing rate, so the same source data feeds both payroll and project costing.

Approvals and payroll posting are handled the ERPNext way. The Overtime Slip runs through a Frappe Workflow (Draft → Submitted → Approved/Rejected) with role-based permissions, and on approval a server script creates the matching Additional Salary record against the correct salary component and payroll period, so overtime flows into the next Salary Slip with no manual re-entry and a clean audit trail from clock-in to pay line. Client scripts surface a live OT preview on the form; whitelisted methods expose the calculations over the Frappe REST API so a kiosk, mobile app, or biometric integration can push check-ins and read back OT figures. Everything respects your role profiles, and the scheduler recalculation is idempotent so re-runs never double-count.

Because this is build-to-order, nothing is downloaded and dropped onto your production site blind. We start with a short scoping call to confirm your shift patterns, multiplier rules, holiday and rest-day logic, salary components, and which flows need timesheets versus OT-only. We then build the app against your exact ruleset, install and validate it on a staging copy of your ERPNext v15 or v16 site, run UAT with your HR and payroll teams on real attendance data, and only then cut over to production with a rollback plan in hand. Typical delivery is 2-4 weeks from confirmed scope, and you receive the full source and git repository so nothing is locked to us.