Simulating and adjusting

When to use

Use simulation when you want to know what a pay period will cost before creating a real run, for example after a policy change or when the CFO asks for an estimate. Use salary adjustments when one person’s pay must change with an audit trail.

Before you start

Permissions: payroll:read to simulate (it writes nothing); payroll:write to raise adjustments; payroll:approve to approve them.
Toggle people.payroll_adjustment_approval_required (default on): adjustments need approval before they take effect.
Toggle people.salary_change_approval_required (default on): salary changes need approval.

Simulate before you commit

Go to Payroll → Payroll Simulation to preview the full run — gross, deductions, and net — without creating a live run, so you can catch surprises early.

Make individual adjustments

Go to Payroll → Salary Adjustments to change a specific employee’s pay mid-cycle (raise, correction, one-off) with a reason recorded for audit.

Re-simulate and confirm

Re-run the simulation after adjustments to confirm the totals before starting the live run.

Payroll — Simulation preview comparing gross, PIT, BHXH, and net totals

What simulation does and does not do

It calculates gross pay, PIT, BHXH and net pay for the period as a preview, without writing a live run or posting to the GL.
Line managers can review adjustment proposals on Payroll → Salary Adjustments (/payroll/adjustments) before the period closes.

Tips & common mistakes

Simulate before every large change, then compare against the previous period to spot outliers.
Always enter a clear reason on an adjustment; it is what auditors will read.
An adjustment after the period is finalised does not rewrite that period; use the correction paths instead.
Merit increases proposed from Performance arrive as adjustment requests and follow the same approval.

Salary structures, models, and variable pay Correcting a finalised run