Retro Timesheet Adjustment: Fix Closed Pay Periods Without Re-Opening Them

The problem this kills

It's two days into the new pay period and an employee messages you: "I forgot to log 6 hours from two weeks ago." The period those hours belong to is already closed, approved, and paid. Now you're stuck. Re-opening the old period risks recalculating taxes, benefits, and accruals that were already finalized. Editing the locked timesheet by hand leaves no trace of what changed or why. And just "adding it somewhere" on the next run, off the books, is exactly how payroll errors and disputes are born.

Retro pay corrections are one of the most error-prone, least-controlled moments in payroll. They happen all the time, they involve real money, and most teams handle them with a sticky note and a manual override. What you actually need is a safe, repeatable way to say: here's the period, here's what the hours should have been, here's the difference, a manager signed off on it with a reason, and the correction gets paid forward — with the original history left exactly as it was. You do not need to be a developer to build that.

What you'll build

A simple internal web tool for your payroll team. You select a closed pay period and an employee, and the tool shows you their already-approved hours for that period. You enter the corrected hours. The tool computes the delta — just the change, nothing else — and never silently edits the closed history. A payroll manager (a higher authority than a normal timesheet approver) reviews the original versus the requested hours, sees the delta, and approves it with a reason code. Only then does the tool produce a clean adjustment line, forward-dated to the next run, exported in the exact columns your payroll system imports. The original period stays intact, with a linked adjustment record so anyone can trace the correction back to where it came from.

What's inside the Implementation Plan

The downloadable plan is a step-by-step file you paste into an AI coding agent. It opens by interviewing you about your business — how corrections reach you today, what your pay periods and timesheet system look like, the exact fields and codes in your data, your reason codes, who is allowed to approve a retro change, and how far back you'll let adjustments reach. It reads a short spec back to you for a thumbs-up, then builds the tool around your answers instead of a generic template. From there it walks the agent through the data model, importing closed periods, the delta calculation, the elevated manager-approval gate, the forward-dated adjustment record, and the next-run export. Every step ends with a ready-to-copy prompt.

The governance it includes (this is the point)

This isn't a toy. The plan builds in the controls payroll demands: login so only your team can use it, row-level security so people only see their own organization's data, a complete audit trail of every adjustment, approval, and reason (who, what, when, and why), and a hard human-approval gate by an elevated manager role before any adjustment is committed. Closed periods are treated as locked history — the tool never mutates them, it always creates a separate forward-dated adjustment. A configurable cap limits how far back a correction can reach, and a duplicate guard (employee + original period + adjustment) stops the same fix from being processed twice.

Who it's for

Payroll specialists, payroll managers, and HR/ops leads who own the timesheet-to-pay flow and keep getting "I forgot to log my hours" after the period closed. If you can describe how your pay periods work and what an approved timesheet looks like, you can build this.

You've got this — open the plan, paste the first prompt, and you'll be handling your first retro correction safely this weekend.