Published: 23 October 2026 · By Ameer Hamza
Running payroll in-house works until it doesn't: a key person goes on leave, you hire in a second state or country, or a filing deadline slips. Outsourcing fixes that, but only if the handover is planned. Most payroll problems after a switch come from missing data, unclear responsibilities or no test run.
The short answer: to outsource payroll, decide what you are handing over, collect your employee and year-to-date data, agree who is responsible for each task, run at least one parallel payroll, then go live and check the first reports. This guide turns that into a 30-day plan, with the country rules you still own after the switch.
Before You Start: One Rule That Doesn't Change
You can outsource the work, but not the legal responsibility. In the USA, the IRS states that the employer remains responsible for depositing and paying federal employment taxes, even when a payroll provider makes the payments. The same principle applies in the UK, Canada and Australia. That is why the checks in this plan matter.
The 30-Day Switch Plan
When | What happens | Who leads |
|---|---|---|
Days 1–5 | Agree scope: which countries, pay groups, benefits and reports move over. Sign the agreement and a data-protection clause. | You and the provider |
Days 6–12 | Send employee records, pay rates, tax codes and year-to-date totals. Provider sets up your payroll. | You send, provider builds |
Days 13–20 | Parallel run: both payrolls calculate the same pay period. Compare every payslip and fix differences. | Provider runs, you check |
Days 21–25 | Sign-off: approve the go-live date, approval steps and cut-off dates for changes. | You |
Days 26–30 | First live payroll, filings and payments. Review the reports and employee questions. | Provider runs, you approve |
The Data Checklist
Legal employer details, tax and employer registration numbers for each country
Every employee's name, address, start date, tax ID and bank details
Pay rates, pay frequency, overtime rules and allowances
Tax codes or withholding forms, pension or retirement details and benefit deductions
Year-to-date earnings, taxes and deductions for every employee
Leave balances, if the provider will track leave
Your last three payroll reports, to compare against the parallel run
Who Does What After the Switch
Task | You | Payroll provider |
|---|---|---|
Hours, new starters, leavers and pay changes | Send before cut-off | Process |
Pay calculations and payslips | Approve | Prepare |
Tax filings and reports to authorities | Stay legally responsible | Prepare and submit |
Payments to staff and tax offices | Fund on time | Arrange |
Year-end forms | Check | Prepare |
Employee pay questions | First contact, if agreed | Answer details |
The Rules You Still Own, by Country
Country | Key payroll rules to keep an eye on |
|---|---|
USA | Federal employment tax deposits stay the employer's responsibility, even when a provider pays them. State payroll taxes and new-hire reporting apply too. |
UK | Each pay run is reported to HMRC through a Full Payment Submission sent on or before payday. |
Canada | Employers deduct CPP contributions, EI premiums and income tax, remit them to the CRA, and file T4 information returns by the last day of February. |
Australia | Each pay run is reported through Single Touch Payroll on or before payday. From 1 July 2026, super guarantee contributions of 12% must reach the employee's fund within 7 business days of payday. |
6 Questions to Ask a Payroll Provider
Which countries, states and provinces can you run payroll for?
Will you run a parallel payroll before we go live?
What are the cut-off dates for changes each pay period?
How do you protect employee data, and where is it stored?
Who checks the filings, and what happens if one is late?
What reports will we get each pay period and at year end?
Common Mistakes to Avoid
Switching mid-quarter without year-to-date data: year-end forms will be wrong.
Skipping the parallel run: small rate or deduction errors reach real payslips.
No approval step: always review the payroll summary before payment.
Unclear cut-offs: late changes lead to off-cycle payments and unhappy staff.
Payroll is often the first thing businesses outsource, followed by employee outsourcing and dedicated offshore staff. To keep policies and filings in line as you grow, see our HR compliance service, and read what different hiring and HR services cost.
Frequently Asked Questions
How long does it take to outsource payroll?
A simple payroll can move in about a month, including a parallel run. Multi-country payrolls take longer.
Can I switch payroll providers in the middle of the year?
Yes, as long as you transfer accurate year-to-date totals for every employee, so year-end forms stay correct.
Am I still responsible if the provider makes a mistake?
Yes. The employer stays legally responsible for payroll taxes and filings, so keep an approval step and check reports every pay period.
What is a parallel payroll run?
Running the same pay period through your old and new payroll at the same time, then comparing every payslip before the new system goes live.
Can one provider run payroll in several countries?
Some can. Ask which countries they cover directly and which they handle through local partners.
Sources and Further Reading
Running payroll: reporting to HMRC (GOV.UK)
Employers' Guide: Payroll Deductions and Remittances (Canada Revenue Agency)
Rules of reporting through STP (Australian Taxation Office)
About Payday Super (Australian Taxation Office)
This article is general information, not tax or legal advice.
Ready to Hand Over Payroll?
Vortexian Tech runs payroll for businesses in the USA, UK, Canada and Australia, including parallel runs and year-to-date transfers. See our payroll outsourcing service or tell us about your team.
