Your details
Combined monthly take-home
£—
£— a year across both jobs
Main job (allowance here)
£—
take-home / month
Second job
£—
take-home / month
NI advantage: because National Insurance is charged per employment, each job gets its own £12,570 NI threshold — two small jobs often beat one big one for NI. Income Tax, however, is charged on the combined total.