Running an extra payroll mid-month
Yes — and by when
An extra run can go out any working day up to the 27th. After that it falls into the following month’s reporting, which is rarely what anyone wants.
What it does to reporting
Each run files its own FPS to HMRC. Two runs in one month means two filings — correct, and expected.
What it costs
Nothing extra on Standard. On Basic it counts as the month’s second run.
Nobody has ever answered what happens when an extra run and a correction land in the same week. Left as a question for you.