The direct route
Employing the person yourself, with no UK company
There is no UK and Australia social security agreement
The UK and Australia used to have a social security agreement, and it ended in 2001. HMRC's list of agreements with contribution provisions shows it as "terminated 28 February 2001", and Australia isn't among the agreement countries in HMRC's employer guide for 2026 to 2027. So no agreement treats an Australian employer as if it were based in the UK, and the UK's own rule decides whether it owes employer's National Insurance.
HMRC's rule is that an employer owes UK employer's National Insurance if it is resident, present or has a place of business in Great Britain. HMRC's manual lists the kind of evidence it looks for, such as a registered office in the UK, fixed premises in the UK, a UK bank account, or the company paying the employee's rent or mortgage, and whether an employer meets the test is a matter of fact.
The DPNI route
An Australian company with no UK place of business has two routes, and on both the company stays the employer. HMRC's manual PAYE20100 lists "A foreign employer who has no address in the United Kingdom from which earnings are paid" among the cases a DPNI is for. The employee sets up a DPNI and pays both their income tax and their employee National Insurance to HMRC under one PAYE reference. We will ask HMRC for the scheme that fits your facts, and they may suggest a different one once they have the full facts.
A direct payment scheme doesn't work like an ordinary payroll. HMRC send the employee a deductions working sheet, the employee fills it in, and the tax and National Insurance payments go to HMRC from them. So you pay the gross salary and don't take any UK tax or National Insurance off it. We do the sums, tell them what's due and when, and they pay HMRC.
One exception to watch: if your employee is made available to work in a UK business, such as a UK client, HMRC's employer guide says that UK business must pay the employer's and the employee's National Insurance instead, where no agreement with employer obligations covers the employee.
Someone you send over from Australia
A local UK hire is in the UK system from the start. Someone you send here for a while is different. For an employee who doesn't normally live or work in the UK and whom you send here temporarily, HMRC's employer guide says National Insurance isn't payable for the first 52 weeks, counted from the first Sunday after they arrive. HMRC's own manual uses an Australian employer with no UK place of business as its example, and the employee becomes liable once those 52 weeks have passed.
Or run UK PAYE in the company's own name
A company with no UK presence doesn't have to run UK PAYE, but it can choose to run it in its own name. Then the company takes the employee's income tax off their pay through its own payroll, and our fees are the company's cost, not the employee's. The employee's National Insurance still has to be paid: the company can pay it through its payroll if it's willing to and HMRC agree, and if not, the employee pays it directly.
A UK PAYE scheme in the company's own name starts at £225 a month plus £8 per payslip, and setting it up costs £350.