Running payroll in-house vs outsourcing it monthly
Quick answer
With a small headcount, a simple pay structure and someone who already understands withholding, keeping payroll in-house controls cost well. Once you add foreign staff, shifts, overtime or several branches, the monthly cycle becomes a risk: one error touches employee tax, social security and internal trust at once. Outsourcing pays off when you need continuity and a second pair of eyes.
Side-by-side facts
| Aspect | Keep it in-house with your own HR | Outsource to a monthly payroll team |
|---|---|---|
| Monthly workload | You close, calculate, review and file every month with no backup | The outside team owns the whole cycle with a reviewer before payout |
| Pay confidentiality | Executive pay data sits with staff who work side by side daily | Data moves outside the staff circle under a confidentiality agreement |
| Continuity when someone resigns | Know-how usually sits with one person; a resignation stalls the cycle | The process lives with the firm, so handover happens without a stop |
| Exposure in a look-back audit | Papers scatter and must be pulled together in a hurry when requested | Each month is filed as a ready bundle on the day the cycle closes |
| Visible and hidden cost | Staff salary plus management review time, which rarely gets counted | A clear monthly fee that tracks actual headcount |
| Handling complex cases | Foreign staff, severance or multi-branch cases mean researching each time | Someone has run the same pattern before and can benchmark the call |
Choose Keep it in-house with your own HR when
- Under ten staff on a fixed pay structure
- Someone already understands employee withholding
- No foreign staff and no routine overtime
- You want pay data kept strictly inside the organisation
Choose Outsource to a monthly payroll team when
- Several staff groups, branches or foreign employees
- You have filed late or recalculated after an error
- You want management out of the monthly number-checking
- An audit or a future sale of the business is coming
Documents to prepare
- Staff register with start dates and current pay rates
- Employment contracts and past pay-adjustment letters
- Recurring deductions and other paid items such as travel allowance
- Proof of the latest tax and contribution submissions
- Leave, overtime and actual pay-cycle policies
Step by step
1. Survey the current state
Count staff by pay group, check the register against what is actually paid, and mark every step still done by hand.
Typical duration: 3–5 days
2. Pick the cut-over cycle
Move at the start of a month after the previous cycle has closed, so no single month has two owners.
Typical duration: 1 week
3. Hand over the base data and run in parallel
In the first month calculate both ways and reconcile line by line; every difference must be explainable before payout.
Typical duration: One pay cycle
4. Set the routine and the approval path
Fix the data-in date, the review date, the approval date and who signs off, in writing.
Typical duration: 2–3 days
5. Review yearly and prepare the annual summary
At year end confirm each person's cumulative figures match every monthly submission before issuing withholding certificates.
Typical duration: Once a year
What usually goes wrong
- Cutting over mid-month and breaking cumulative per-person figures
- Handing over only net figures without the deduction detail
- Missing joiner and leaver notices before the contribution deadline
- Relying on a spreadsheet whose hidden formulas nobody can explain
- Sending pay data with no confidentiality agreement in place
Why an adviser beats a template
Payroll is the kind of work that cannot fail quietly: staff notice immediately and the agencies notice later. We treat it as advisory work rather than arithmetic, reviewing the pay structure, the contracts and the benefit policy together so the clause that will become a dispute is flagged before it does. Fifteen-plus years of files means we have seen the pattern before and can say when the fix belongs in the policy, not in the numbers.
Frequently asked questions
Can payroll move mid-year?
Yes, provided the year-to-date figures per person come across in full, because employee tax is computed on the whole year rather than the month of the move.
Will staff know an outside team is involved?
Payslips still carry your company name; you decide whether staff questions go to your HR or straight to our team.
What if past submissions were wrong?
Trace it month by month to see whether the error was in the wage base or the rate, then file the corrections in date order. Fixing it systematically beats waiting to be asked.
Is the fee headcount-based or fixed?
Usually it tracks the headcount actually in the cycle and how complex the pay structure is, since shifts and overtime take more review time than fixed salaries.
Can we keep doing it and just have it reviewed?
Yes. We review the cycle before payout and the submissions after filing, which suits teams that exist but want a second confirmation.
We would rather not touch this at all
We take it from building the staff register, calculating pay and deductions, issuing payslips, filing tax and contributions on time, keeping each month audit-ready, through to the year-end summaries — with a named adviser your HR can ask any cycle.
Official sources
Not sure which route fits your case?
Call +66-92-017-0000, email contact@tla.co.th, or message us on LINE. Monday to Saturday, 09:00–18:00 Bangkok time, in English or Thai.