Outsourced accounting firm vs an in-house accountant
Quick answer
The deciding number is not the monthly fee: it is documents per month and filings per year. A business under a few hundred documents a month usually lands at a lower all-in cost with a firm, paying only for work that actually happens and getting a registered bookkeeper without salary, social security and leave on top. Once there is inventory, several branches, or a need to close figures weekly for decisions, having someone in the office starts to earn its keep.
Related subject area
Head of Accounting
Financial statements and TFRS for NPAEs specialist
This accounting subject area covers bookkeeping, closing and applicable reporting standards. It is not a verified individual's biography or licence. Statutory audit is separate from account preparation and agreed with a CPA Partner.
Supporting subject area
Head of Tax
Tax subject area
This role is not evidence of an individual reviewing this page. Consult its scoped references · content date 2026-08
View role scopeSide-by-side comparison
| Aspect | Hand the books to an outside accounting firm | Employ an accountant on the payroll |
|---|---|---|
| Visible and hidden cost | A scoped fee that moves with real document volume | Salary, bonus, social security, provident fund, equipment and continuing training |
| What happens when the person is away | A backup takes over because the file sits in a shared system | Work stalls at resignation or parental leave and must be handed over again |
| Who signs as the bookkeeper | The firm's registered bookkeeper, with the required CPD hours | The employee must qualify and register; the company must track this |
| Breadth of exposure | Sees many industries, so similar tax issues have been met before | Deep on one company, but must source new knowledge alone |
| Day-to-day availability | Responds on an agreed cycle, suited to plannable work | Answers on the spot, suited to businesses deciding constantly |
| Internal control | Recording and review are separated by the firm's own structure | One person records, pays and reconciles — the weakness auditors flag most |
| When a filing turns out wrong | Scope and liability are written into the engagement | The company absorbs the surcharge and penalty itself |
Choose this when — Hand the books to an outside accounting firm
- Monthly documents are still modest and mostly repeat the same patterns
- You want a registered bookkeeper from month one without a hiring cycle
- You want recording and review split from the start
- Growth is still uneven, so you would rather not lock in a fixed cost
Choose this when — Employ an accountant on the payroll
- Inventory must be counted and costed daily
- Management prices and orders off weekly numbers
- Several branches or group companies need reconciling against each other
- Document volume genuinely fills one person's working week
Documents to prepare
- Average input and output tax invoices per month over the last six months
- The list of tax forms the business must file in a year
- Headcount and how wages are paid
- The accounting system in use and who holds access rights
- Carried-over problems such as unfiled statements or balances that will not reconcile
Step-by-step process
1. Count the real workload
Instead of guessing from revenue, count the actual documents in the last three months and multiply by the filing cycles in a year. That number answers the full-time question by itself.
Duration: 1–2 days
2. Price both routes all-in
For the employee route include twelve salaries, bonus, contributions, equipment and training. For the firm route include year-end closing and the annual filing. Compare only at full-year figures.
Duration: 2–3 days
3. Test with a real backlog
Let each route work one genuinely messy month and watch how sharp the questions coming back are. That reveals quality faster than any quotation.
Duration: 1–2 weeks
4. Set the switch point in advance
Decide now at what document volume or branch count you will move in-house or to a hybrid. Setting the trigger early avoids deciding when work has already overflowed.
Duration: half a day
Pitfalls to avoid
- Comparing a monthly fee straight against a salary while forgetting contributions, leave and yearly training
- Letting one employee issue payments, record entries and reconcile the bank with no second pair of eyes
- Changing provider mid-year without handing over the asset register and opening balances, so year-end will not close
- Assuming outsourcing ends the duty, when directors still sign off the financial statements
- Not keeping the accounting system's admin rights with the company, leaving data stranded at the end of the engagement
Frequently asked questions
Can the two be mixed?
Yes, and mid-sized businesses pick it most often: an internal staffer handles daily receipts, payments and document collection, while the outside firm takes closing, tax computation and review. You get internal speed with an external second look.
Is changing firms mid-year damaging?
Not if the handover is complete. You need opening balances that tie to last year's statements, the fixed-asset register with accumulated depreciation, party-level debtor and creditor detail, and every tax form already filed this year. Miss one and year-end becomes rework.
A new company with no revenue — are books still required?
Yes. The duty to keep accounts and file statements starts at registration, not at first sale. A pre-revenue company still needs a bookkeeper, a closing and an on-time filing, otherwise penalties accumulate quietly until the day the company is actually needed.
How do you judge a firm's quality?
Judge by the questions they ask back, not the price. A firm doing real work asks about contracts that change the withholding rate, how stock is counted, and who approves payments. One that asks nothing usually files only what it was handed.
If we hire in-house, what else is needed?
Three things get forgotten: an outside reviewer or a director who can read the statements so the recorder is not checking their own work; a cover plan for parental leave or resignation; and system rights held by the company rather than tied to the employee's personal email.
Decision checklist
Tick each line. If more than two remain unanswered, ask us before you commit.
Where to read next
More than a filing service — we advise you
Before signing either way, ask: if the Revenue Department requests two years of documents next month, who can produce them within a week? The answer points to the right structure more accurately than any comparison table. We can count the workload and price both routes for you first, with no commitment.
Sources
Other decisions usually made at the same time
- BOI vs Amity Treaty for foreign-owned business
- In-house accountant vs outsourced accounting firm
- Sole proprietorship vs limited company in Thailand
- Filing a trademark in Thailand versus filing through the Madrid System
- Switching accounting firm mid-year vs waiting for year end
- Monthly bookkeeping vs a single year-end catch-up
- Registering for VAT early vs waiting for the threshold
- Running payroll in-house vs outsourcing it
- Part-time accountant vs a full-time hire
- Changing the accounting period vs keeping it
- e-Tax Invoice vs paper tax invoice
- Closing a company vs keeping it dormant
- Employee vs freelance contractor: tax and accounting
- Virtual office vs a leased office when you need VAT registration
Thai Law & Accounting Services — attorneys and licensed accountants · Reviewed by a Notarial Services Attorney registered with the Lawyers Council of Thailand. · Updated 2026-08
Information as of August 2026. Government fees and processing times change — verify with the relevant agency before acting, or let our team verify for you.