Key takeaways
- Retention is a contractual arrangement. Private law sets no rate, so the rate, cap, release, set-off and documents must be written clearly.
- Common market practice: deduct 5–10% per progress payment, cap at 5% of the contract value, release 50% on handover and 50% at the end of the DLP once all defects have been rectified.
- If the tax invoice is issued for the amount actually received, VAT and WHT are calculated on the amount actually paid, while retention is taxed when it is released or set off.
- Retention withheld is a liability of the employer and a contract asset or receivable of the contractor. Reconcile the register to the GL every month.
This content is general practice guidance for private-sector projects and is not legal advice. Actual terms are governed by the contract. Legal counsel and an accounting firm should confirm them before use. Public-sector projects are governed instead by public procurement laws and regulations. All figures are hypothetical examples.
Framework and principles
Who uses which part
| Role | Position on retention | Sections to read |
|---|---|---|
| Project owner | Party that deducts retention from the main contractor or subcontractor | Terms, deductions, releases, bank guarantees, employer's accounts, controls |
| Main contractor | Has retention deducted by the owner and deducts it from subcontractors | All sections, especially back-to-back |
| Subcontractor | Party subject to the deduction | Deductions, releases and the contractor-side accounts |
Definitions
| Term | Meaning |
|---|---|
| Retention | Money deducted from progress payments to secure completion of the work and rectification of defects. It is released when the contract conditions are met. |
| Cap | The maximum cumulative retention. Once it is reached, deductions stop. |
| Payment Certificate | The certificate for the progress payment, measured by the project team or QS and used as the basis for payment and retention deductions. |
| Practical Completion | The handover date, which may come with a punch list. It is the point of the first release and the start of the DLP. |
| DLP | The defects liability period under the contract, usually 12 months from handover. |
| Back-charge | The actual cost the employer pays to rectify work in place of the contractor, which is then set off. |
| Bank Guarantee | A bank guarantee lodged in place of cash, callable for payment on a breach of conditions. |
| Retention Register | A register tracking retention for each contract. |
Seven principles
| # | Principle | Practical effect |
|---|---|---|
| 1 | Retention is a contractual arrangement. Private law sets no rate. | Specify the rate, cap, release conditions and set-off clearly. Make no deductions outside the contract. |
| 2 | Deduct from the certified value of work in every payment until the cap is reached. | Always use the payment certificate as the basis, not the amount the contractor claims. |
| 3 | WHT and VAT are calculated on the actual payment date, on the amount actually paid. | Retention is taxed when it is repaid or set off. |
| 4 | Retention is a liability of the employer and an asset of the contractor. | Keep separate accounts and reconcile to the register every month. |
| 5 | Release only when the conditions and documents are complete. | The first release is at handover. The final release is at the end of the DLP, once all defects have been rectified. |
| 6 | The main contractor is jointly liable for the wages of a subcontractor's employees. | Request evidence of wages and social security payments before releasing retention. |
| 7 | A contractual DLP does not remove statutory liability. | Defects in a building on land can give rise to liability for up to 5 years under Section 600 of the Civil and Commercial Code. |
Roles and responsibilities (RACI)
| Activity | Project/QS | Contract | Finance | Account | Approver |
|---|---|---|---|---|---|
| Set the retention terms in the contract | C | R | C | C | A |
| Measure progress and issue the payment certificate | R | I | I | I | A |
| Calculate retention, VAT and WHT | C | – | C | R | A |
| Pay progress payments and release retention | – | – | R | C | A |
| Record in the accounts, update the register and issue the 50 bis certificate | – | – | C | R | I |
| Inspect and accept the work, and inspect defects at the end of the DLP | R | C | – | I | A |
| Receive, check and return the bank guarantee | I | R | R | C | A |
| Set off back-charges and penalties | R | R | C | R | A |
R = Responsible, A = Approver, C = Consulted, I = Informed. Legal counsel should also review any dispute or contract termination.
Relevant laws and standards
| Topic | Law/standard | Key points |
|---|---|---|
| Hire of work | Civil and Commercial Code, ss. 587, 602 | The price is payable on acceptance of the work. If the work is delivered in parts, it is payable in parts. |
| Rectification of work | Civil and Commercial Code, s. 594 | The employer may require rectification, or have a third party do the work at the contractor's expense. |
| Defects | Civil and Commercial Code, ss. 600, 601 | 1 year from delivery, or 5 years for a building on land other than a timber house. The limitation period is 1 year from when the defect arises. |
| Set-off | Civil and Commercial Code, ss. 341–348 | Rectification costs and damages may be set off once the debt is due and the contract does not prohibit it. |
| Contractual penalty | Civil and Commercial Code, ss. 379–383 | May be deducted as provided in the contract. The court may reduce it if it is disproportionately high. |
| Default interest | Civil and Commercial Code, s. 224 | Late release of retention risks default interest, currently 5% per annum. Check the rate on the date of use. |
| Guarantee | Civil and Commercial Code, s. 680 onwards | Bank guarantee |
| Subcontractor's employees | Labour Protection Act 1998, s. 12 | The main contractor and every tier of subcontractor are jointly liable for wages and compensation. |
| WHT | Revenue Code, ss. 3 Tredecim, 50 bis, 39; Tor.Por. 4/1985 | Wages for hire of work: 3%. Payment includes set-off. |
| VAT | Revenue Code, ss. 78/1, 82/3, 86 | Liability on services arises when payment is received or a tax invoice is issued, whichever is earlier. |
| Stamp duty | Stamp duty tariff, items 4 and 17 | Hire of work: THB 1 per THB 1,000. Guarantees above THB 10,000: THB 10. |
| Account | TFRS 15 paragraphs 105–108, TFRS 9, TAS 1, TFRS for NPAEs | Contract asset, amortised cost, current classification |
Standard contract terms to specify
| Topic | Recommended approach | Notes |
|---|---|---|
| Deduction rate per payment | 5–10% of the certified value of work | Systems work or high-risk work may warrant a higher rate |
| Ceiling | 5% of the contract value, adjusted for additions and omissions | Stop deducting once the cap is reached |
| First release | 50% on handover | A punch list is permitted, but it needs a plan and a deadline |
| Final release | 50% at the end of the DLP, once all defects have been rectified | Release within a set period, for example 30 days from when the conditions are met |
| DLP | 12 months from handover. Systems work may be 24 months | A subcontractor's DLP should not end before the DLP with the owner |
| BG in place of cash | Unconditional, callable on demand, valid until the end of the DLP plus 30–60 days | Specify the form and the acceptable banks |
| Set-off | Back-charges, penalties and damages may be deducted after written notice | State the procedure and the period allowed for rectification first |
| Tax invoice | Issued for the amount actually received in each payment, and again when retention is received back | Prevents VAT from arising before the money is received |
| Evidence of wages | Before release, the contractor must show evidence of payment of wages and social security | Protects against joint liability under s. 12 |
| Interest | Retention bears no interest unless the contract provides for it | Release on time to avoid default interest |
Contractual DLP vs statutory liability
Contractual DLP
For example 12 months, the period in which the employer holds retention or a BG so that defects can be rectified quickly.
Statutory liability
Section 600 of the Civil and Commercial Code sets 1 year, or 5 years for a building on land. Even after retention has been released, a claim can still be made within the 1-year limitation period from when the defect arose, under s. 601.
Clauses that exclude or limit liability may be ineffective in some cases. Have legal counsel review them.
Deducting retention from each progress payment
- The subcontractor submits the progress invoice and progress report to the contracts team.
- The project team or QS measures the work and issues the payment certificate.
- Accounts calculates retention at the agreed rate and checks that it does not exceed the cap.
- Calculate VAT and WHT on the amount actually paid.
- The approver approves payment in line with the certificate.
- Finance transfers the net amount to an account in the contractor's name.
- Accounts records the retention payable, updates the register and issues the 50 bis certificate.
Retention this period = MIN(work value this period × deduction rate, cap − cumulative retention before this period)
Payment before VAT = work value this period − retention this period − other deductions under the contract
Net payment = payment + 7% VAT − 3% WHT
Example: a THB 10,000,000 subcontract, 4 progress payments, 5% deduction, 5% cap
| Item (THB) | Per payment | Total, 4 payments |
|---|---|---|
| Certified work value | 2,500,000.00 | 10,000,000.00 |
| Less: retention 5% | (125,000.00) | (500,000.00) |
| Payment amount before VAT | 2,375,000.00 | 9,500,000.00 |
| VAT 7% | 166,250.00 | 665,000.00 |
| Less: WHT 3% | (71,250.00) | (285,000.00) |
| Net payment | 2,470,000.00 | 9,880,000.00 |
Cumulative retention after payment 4 is THB 500,000, exactly the cap of 5% of the contract value.
Tax: timing of WHT and VAT
| Tax | When retention is deducted | When retention is released |
|---|---|---|
| WHT 3%: juristic person PND 53, or individual PND 3 | Deducted only on the amount actually paid | Deducted on the retention amount released, including any amount set off |
| VAT 7% on services | The contractor issues a tax invoice for the amount received | The contractor issues a tax invoice when retention is received back |
Confirm with your accounting firm before use: if the contractor issues a tax invoice for the full progress payment before being paid, VAT liability arises immediately on issue, so the contract should specify how invoices are to be issued.
Do not deduct WHT twice: if WHT has already been deducted on the full value of the progress payment, it must not be deducted again when retention is released. Use a single method throughout the contract.
Employer outside the VAT system: for example, a condominium developer that pays SBT cannot claim input VAT credit, so VAT becomes a project cost.
The contractor must recognise revenue, including retention, on an accrual basis under Section 65, paragraph 2 of the Revenue Code, even though the retention has not yet been received. The 7% VAT rate is currently extended to 30 September 2027 under Royal Decree No. 807.
Releasing retention
First release at handover
- The subcontractor notifies completion and requests an inspection.
- The project team or QS inspects and prepares a punch list.
- The approver issues the handover certificate.
- The subcontractor submits a request for release of 50% with the full set of documents.
- The contracts team checks evidence of wage payments and the subcontractor's employees' social security
- Accounting calculates VAT and WHT on the amount released
- Approve and transfer the refund
- Clear the retention payable, update the register and start the DLP count
Release of the final instalment at the end of the DLP
- 30 days ahead: schedule a joint defect inspection
- Joint defect inspection: all parties sign the inspection results
- Defects found: notify the subcontractor in writing, with a deadline for rectification
- Subcontractor does not rectify by the deadline: hire others to fix the defects and keep back-charge evidence
- Subcontractor submits a claim for the remaining 50% with the Final Account
- Check evidence of wage payments and the subcontractor's employees' social security
- Deduct the back-charge and calculate VAT and WHT on the amount released
- Approve, transfer the money, close the register and issue the 50 Tawi certificate
Steps 3–4 apply only if defects are found. If none are found, go straight to step 5.
Example of a retention release
| Item (THB) | First release 50% | Final, no defects | Final, with back-charge |
|---|---|---|---|
| Retention released | 250,000.00 | 250,000.00 | 250,000.00 |
| VAT 7% | 17,500.00 | 17,500.00 | 17,500.00 |
| Less: WHT 3% | (7,500.00) | (7,500.00) | (7,500.00) |
| Less back-charge | – | – | (80,000.00) |
| Net payment | 260,000.00 | 260,000.00 | 180,000.00 |
Whole contract, no defects: before VAT 10,000,000 + VAT 700,000 − WHT 300,000 = net payment of THB 10,400,000, split into progress payments of THB 9,880,000 and retention release of THB 520,000
In the back-charge case, the contractor's revenue is still based on the full retention of THB 250,000, so tax is calculated on the full amount and then offset by the actual cost of THB 80,000, net of recoverable VAT. A notice letter, a quotation or invoice from the party who rectified the work, and before-and-after photographs are required.
Documents supporting the release
| Document | First release | Final release |
|---|---|---|
| Retention release request letter | Required | Required |
| Handover letter / Certificate of Practical Completion | Required | – |
| Punch list and rectification plan | Required | – |
| As-built drawings, manuals and equipment warranties | Required | – |
| Joint defect inspection result at the end of the DLP, signed | – | Required |
| Final Account signed by both parties | Initial view | Required |
| List of back-charges or penalties, with evidence | If any | If any |
| Evidence of wage payments and social security contributions | Required | Required |
| Letter confirming there are no outstanding claims | Required | Required |
| Invoice or tax invoice for the amount released | Required | Required |
| Original guarantee letter, returned when the contract is closed | – | If any |
Bank guarantee (BG) in place of cash
| Issue | Deducted in cash | Provide a BG |
|---|---|---|
| Contractor's cash flow | 5% is withheld until the end of the DLP | Receives full payment but pays a fee |
| Employer's security | Highest: the money is in hand | High, if unconditional and not yet expired |
| Set-off | Can be deducted immediately | Must call the BG |
| Control workload | Control the register and GL | Control expiry dates, originals and extensions |
| Example cost | No fee | 2% per year × 500,000 × 2 years = THB 20,000 + stamp duty THB 10 = THB 20,010 |
- Subcontractor requests to use a BG in place of cash
- Contracts and legal teams check the bank, amount, conditions and validity period
- Accept the BG and then either stop deducting or return the cash already withheld
- Monitor the expiry date in the register and give advance notice for renewal
- End of DLP with no claims: return the BG
- Issued by an accepted commercial bank, on the employer's form
- Unconditional, payable on written demand
- Value not less than the retention; validity to the end of the DLP plus 30–60 days
- Verify with the issuing bank, keep the original and set a reminder 60 days before expiry
- If expiry is near and defects are not yet fully rectified, extend the validity or call the BG before expiry as the contract allows
Main contractor: back-to-back with subcontractors
A main contractor has retention deducted by the project owner and also deducts retention from its subcontractors, so the terms on both sides must be aligned.
| Item | Contract with project owner | Total subcontracts | Net |
|---|---|---|---|
| Contract value | 50,000,000.00 | 30,000,000.00 | |
| 5% retention | Receivable 2,500,000.00 | Payable 1,500,000.00 | Net amount withheld 1,000,000.00 |
Example of a DLP gap
The main contractor hands over the whole project on 31 December 2027 and the subcontractor hands over its work on 30 June 2027. If the DLP is 12 months for both, the main contractor must release the final instalment to the subcontractor on 30 June 2028 but will receive its release from the project owner on 31 December 2028. It must therefore fund THB 750,000 in advance for about 6 months.
- Set the subcontractor's DLP to end no earlier than the DLP with the project owner, or plan liquidity to cover the gap.
- Pay-when-paid clauses must be written clearly and fairly, and reviewed by legal counsel.
- Push the subcontractor to rectify defects before the project owner's end-of-DLP inspection, because a subcontractor's defects are the main contractor's liability to the project owner.
- Track retention receivables and payables together in the register.
Accounting entries
Employer side
| Event and accounts | Debit | Credit |
|---|---|---|
| Pay progress payment, where a VAT credit can be claimed | ||
| WIP or project cost | 2,500,000.00 | |
| Input VAT | 166,250.00 | |
| WHT payable | 71,250.00 | |
| Retention payable | 125,000.00 | |
| Bank deposit | 2,470,000.00 | |
| Total | 2,666,250.00 | 2,666,250.00 |
| First release | ||
| Retention payable | 250,000.00 | |
| Input VAT | 17,500.00 | |
| WHT payable | 7,500.00 | |
| Bank deposit | 260,000.00 | |
| Total | 267,500.00 | 267,500.00 |
| Final release, with back-charge | ||
| Retention payable | 250,000.00 | |
| Input VAT | 17,500.00 | |
| WHT payable | 7,500.00 | |
| Rectification costs recharged, or subcontractor receivable | 80,000.00 | |
| Bank deposit | 180,000.00 | |
| Total | 267,500.00 | 267,500.00 |
An employer that cannot claim a VAT credit records the VAT as project cost, for example by debiting project cost THB 2,666,250 on the progress payment.
Contractor side
| Event and accounts | Debit | Credit |
|---|---|---|
| Receive progress payment | ||
| Bank deposit | 2,470,000.00 | |
| Withholding tax (WHT) withheld | 71,250.00 | |
| Retention receivable (contract asset) | 125,000.00 | |
| Construction revenue | 2,500,000.00 | |
| Output VAT | 166,250.00 | |
| Total | 2,666,250.00 | 2,666,250.00 |
| Receive retention release | ||
| Bank deposit | 260,000.00 | |
| Withholding tax (WHT) withheld | 7,500.00 | |
| Retention receivable | 250,000.00 | |
| Output VAT | 17,500.00 | |
| Total | 267,500.00 | 267,500.00 |
Under TFRS 15 paragraphs 105–108, retention for which the right to payment still depends on conditions other than the passage of time is presented as a contract asset; once only the passage of time remains, it becomes a receivable. Output VAT on retention arises when payment is received, so it is not recorded at the time of deduction, provided the tax invoice is issued only for the amount received. ECL and back-charges expected to be deducted should also be reviewed.
Presentation
- Separate the portion to be released or received within 12 months as current and the remainder as non-current, in accordance with TAS 1.
- Measure at amortised cost under TFRS 9. Present value discounting is usually immaterial when the collection period is no more than 2 years.
- BGs received are not recorded as assets; control them in the register and disclose them as appropriate.
- Entities applying TFRS for NPAEs present retention receivables or payables, split between current and non-current, and should confirm the policy with the auditor.
Special cases
Subcontractor abandons the work or becomes insolvent
- Record the facts and issue written warnings as the contract requires
- Terminate the contract following the procedure in the contract
- Measure the work done and assess the damages or the cost of hiring others
- Set off against the retention and call the BG
- Claim any shortfall or file a claim for debt repayment
- Check the subcontractor's employees' unpaid wages, because the main contractor is jointly liable
- Where the subcontractor is placed under receivership, set-off must comply with bankruptcy law; consult legal counsel.
- The BG must be called before it expires
Delay penalties and set-off
Penalties can be deducted from progress payments or retention as the contract allows. A penalty that is excessive can be reduced by the court. Set-off counts as a payment, so WHT must be withheld and a tax invoice obtained for the full amount before set-off, and written notice must be given every time, stating the amount, reason and evidence.
Additions and omissions
Adjust the cap to the changed contract value, and deduct retention from additional work at the same rate if the contract so provides. For omitted work, if cumulative retention exceeds the new cap, release the excess in the next payment.
Disputes
Releasing retention late without a reason under the contract risks default interest and damages the relationship with the contractor. Keep evidence at every step: defect notices, photographs, inspection reports, quotations from the party who rectified the work, and the contractor's acknowledgements.
Controls and verification
Retention Register
| Field | Description |
|---|---|
| Contractor, contract number, scope of work | Identifies the contract |
| Contract value including additions and omissions | Used to calculate the cap |
| Deduction rate and cap | Per contract |
| Cumulative deducted, released, balance | Balance must equal the amount in the GL |
| Handover date and end-of-DLP date | Used to set release dates and alerts |
| BG: bank, number, amount, expiry date | Alert when a BG expires before the end of the DLP |
| Status | Deducting, cap reached, first release made, contract closed, in dispute |
Month-end closing and reconciliation
- Close the month's instalment and release entries in the register
- Reconcile the register balance with the retention payable or receivable in the GL
- Check the WHT on each release is included in the PND return and that 50 Tawi certificates have all been issued
- Report items due for release and BGs expiring within the next 90 days
- Sign off the reconciliation
Common differences are: a back-charge set off but the register not adjusted; a release paid but the payable not cleared; and the current classification not updated to the actual dates.
Red Flags
| # | Signal | Action required |
|---|---|---|
| 1 | Deduction above the cap, or not made as the contract requires | Correct in the next payment and notify the contractor |
| 2 | Release made before a handover letter exists | Suspend and check the approval authority |
| 3 | Release made without evidence of wage payments | Request the evidence before paying |
| 4 | BG expires before the end of the DLP | Request an extension or call the BG |
| 5 | Register balance does not match the GL | Reconcile before month-end closing |
| 6 | WHT deducted twice | Use a single method throughout the contract |
| 7 | 50 Tawi certificate not issued on release | Issue it and file the returns in full |
| 8 | Tax invoice for the full instalment but payment not made in full | Agree the invoicing method in the contract |
| 9 | Back-charge without a notice letter or evidence | No set-off until the documents are complete |
| 10 | Retention outstanding well past its due date | Review the reason and the interest risk |
Tax penalties
| Case | Result | Law |
|---|---|---|
| WHT not withheld, or withheld in part | The payer is jointly liable with the recipient | Revenue Code, s.54 |
| PND return filed late | Surcharge of 1.5% per month | s.27 |
| Incorrect tax invoice used | Input VAT cannot be claimed | s.82/5, 86/4 |
Retention release request form
| Information to complete |
|---|
| Contractor and contract number |
| Release stage: first or final |
| Handover date and end-of-DLP date |
| Cumulative retention deducted and amount requested |
| Set-off items with evidence |
| VAT, WHT and net payment |
| All attachments as listed in the checklist |
| Opinion of the project team or QS, accounting, and approver, with dates |
Draft retention clause
- The employer will deduct retention at [5]% of the certified value of work in each payment until cumulative retention equals [5]% of the contract value, including additions and omissions. Retention bears no interest.
- The employer will release [50]% of the retention within [30] days of the handover date, and the remainder within [30] days of the end of the [12]-month defects liability period, once the contractor has fully rectified the defects.
- The contractor may, instead of a cash deduction, provide a bank guarantee acceptable to the employer, in the employer's form, unconditional and payable on demand, valid until the end of the warranty period plus [60] days.
- If the contractor fails to rectify the work within the time stated in the employer's written notice, the employer may have a third party carry out the rectification and may deduct the actual costs, penalties or damages from the retention or from any other sums payable to the contractor, or enforce them against the bank guarantee.
- The contractor will issue tax invoices for the amount actually received in each progress payment and when the retention is refunded.
- Before each release of retention, the contractor must provide evidence of payment of wages and social security contributions for employees working on the project, and a letter confirming that there are no outstanding claims.
Figures in [ ] are to be adjusted as agreed and reviewed by legal counsel before use.
Checklist for deductions and releases
| Steps | Checklist item |
|---|---|
| Before signing the contract | Rate, cap, release, DLP, BG, set-off, invoicing and complete wage evidence |
| Before signing the contract | Stamp duty on a contract for work: THB 1 per THB 1,000 |
| Every progress payment | Payment certificate signed and retention not above the cap |
| Every progress payment | VAT and WHT on the amount actually paid; issue the 50 Bis certificate and file returns on time |
| Every progress payment | Record the retention payable and update the register |
| Handover of the works | Handover letter, punch list, and the DLP start and end dates recorded |
| First release | Documents complete and wage evidence provided |
| 30 days before the end of the DLP | Joint defect inspection and BG expiry check |
| Final release | Final account, back-charges supported by evidence, and BG returned |
| Monthly | Reconcile the register with the GL and report amounts due for release within 90 days |
Points to confirm before use
| # | Issue | Confirmed by |
|---|---|---|
| 1 | WHT method for retention: use a single method throughout the contract | Accounting firm |
| 2 | The contractor's method of issuing tax invoices and the employer's VAT status | Accounting firm |
| 3 | Classification of retention on the contractor's side and the applicable standard | Auditor |
| 4 | Set-off clauses, pay-when-paid and limitation of liability | Legal counsel |
| 5 | BG form and accepted banks | Contracts and finance team |
| 6 | Public-sector projects are governed by public procurement regulations instead | Contracts team |