An increment effective from April, approved in June, processed in July. Three months of arrears land in the July payslip.
Those arrears are about April, May and June. They are paid in July. Most payroll processes record only the second, and everything downstream inherits the problem.
Why one month is not enough
Statutory computation. PF and ESI are computed against the period the wages relate to. An arrear collapsed into July is computed as though it were July's wages — which produces a different figure, and a contribution that does not reconcile against the months it belonged to.
The registers. A wage register that shows an unexplained spike in July, with no indication of what it covers, is a register that raises a question rather than answering one.
Section 89 relief. Where arrears relate to earlier financial years, relief may be available to the employee — and computing it requires the year-wise breakup. If nobody recorded which months the arrears covered, that breakup has to be reconstructed, usually by the employee, usually in July when they are filing.
The convenient shortcut
Adding arrears as a single lump-sum allowance in the current month is quick, and payroll balances afterwards. It is the reason most companies cannot answer a straightforward question about their own payments six months later.
A lump line cannot tell you, an auditor, or the employee which months the money was earned in. The information was not lost — it was never captured.
Do it at the point of entry
The fix is not a reconciliation exercise. It is recording, when the arrear is created, the period it relates to alongside the period it is paid in. Everything else follows: the statutory computation reads the right period, the register explains itself, and the year-wise breakup exists without anybody reconstructing it.
A related trap: mid-month increments
An increment effective on the 14th is not a full month at the old rate or the new one. It is prorated across the two, and where it also moves basic, the statutory base moves with it from that date. Applying the new rate to the whole month is the same category of error as collapsing arrears — a small simplification that produces a number nobody can later derive.