By KYN AI Advisory Team — AI implementation specialists, Singapore
An agent can read a bill, extract the GST amount and the supplier's GST registration number, and propose a tax code. An accountant should confirm anything that depends on judgement: whether the cost is claimable, whether the supplier is validly registered, whether reverse charge applies, and any non-routine case. Use this checklist to split the work. It is general information for Singapore businesses, not tax advice. Check current rules on IRAS.
Why split the work at all?
Coding GST on bills is repetitive. Most bills come from the same suppliers and repeat the same treatment. That is what an agent does well.
But a small share of bills carry real tax risk. A wrong claim reaches your GST return, and the return is a filing under your company's name. So the design is: the agent handles the routine bulk and flags the rest, and a named person confirms before anything is filed. The same principle applies to every filing: filings wait for a named person.
What can an agent code reliably?
These are rule-based checks with a right answer, so they suit automation.
- Read the tax lines. Extract the GST amount, the pre-tax amount and the total. Check that they add up, in code.
- Find the supplier's registration number. Extract it from the bill and check that its format is valid.
- Check the document type. A tax invoice differs from a receipt, a quote or a statement. Only a valid tax invoice normally supports a claim.
- Apply the supplier's usual code. If the last twelve bills from a supplier were standard-rated and claimable, propose the same.
- Flag a change. Same supplier, different tax treatment this time: flag it.
- Convert currency. For foreign-currency bills, apply the rate from a source you set, and record it.
- Detect duplicates. The same bill number from the same supplier must not be claimed twice.
Every proposal shows the evidence: the text of the line it read.
What must an accountant confirm?
These need judgement, context or a reading of the rules.
| Item | Why a person decides | |---|---| | Is the cost claimable at all? | Some costs are not claimable under the rules, and the use of the item matters | | Is the supplier validly GST-registered? | A number on a bill is a claim, not proof. Check it against the official register | | Does the bill meet tax invoice requirements? | Missing details can block a claim | | Overseas supplier of digital services | May need reverse charge treatment | | Imports and goods | Customs documents and import GST follow a separate path | | Partial or mixed-use items | Needs an apportionment decision | | Exempt or zero-rated supplies | Treatment affects the return | | Credit notes and adjustments | Affect earlier periods | | Bad debt, disposal of assets, stock taken for own use | Special rules |
The agent should not guess on these. It tags the bill "needs review", states why, and moves on.
Read the current rules on the IRAS GST pages and confirm with your accountant. Rules, rates and thresholds change, and this article states none of them for that reason.
How should the workflow run?
- The agent reads the bill and proposes: account, tax code, claimable or not.
- Rules apply the supplier's history and your policy table.
- Bills split into three queues.
- Routine. Known supplier, usual code, totals match. Batch approval by the bookkeeper.
- Review. New supplier, changed treatment, or any item in the table above. The accountant decides.
- Reject. Not a tax invoice, a duplicate, or a failed check.
- Approved bills post to the ledger.
- Before each return, the accountant reviews a GST summary by code with a drill-down to the source bills.
- A named person files.
This mirrors how supplier bills are collected in how an agent reads supplier bills from Gmail into your books.
How do you check the agent's GST coding?
Test before trust.
- Take 100 bills from a quarter your accountant already finalised. Run the agent. Compare code by code.
- Count wrong claims separately from missed claims. A wrong claim is the costlier error because it reaches the return.
- Set the pass mark for wrong claims at zero in the routine queue. Anything uncertain should move to review.
- Retest when the supplier mix changes or the rules change.
The testing method is in hallucination checks for business agents. For a receipt-side view, see how to scan receipts for GST claims in Singapore.
What records should you keep?
Keep the original bill, the extracted fields, the proposed code, the person who approved it and the time. Those four items answer most questions in a review. Check the record-keeping period with IRAS, and retain longer if your auditor asks.
What does a worked example of a split look like?
Take five bills from one week (illustrative). The agent handles each according to how routine it is.
| Bill | Agent proposal | Who confirms | |---|---|---| | Monthly software subscription, same supplier as last year | Software expense, standard tax code from history | Batch approval | | Local stationery supplier, registered, standard purchase | Office expense, standard tax code | Batch approval | | Overseas cloud service, no local tax charged | Software expense, flagged as an overseas purchase | Accountant | | Client entertainment dinner | Entertainment expense, flagged for claimability | Accountant | | Supplier with no registration number on the bill | Held, tax code left blank | Accountant |
The first two are the volume. The last three are the judgement. The flags are rules in code, not model opinions, so the same bill always gets the same flag.
Keep one rule table that the accountant owns. When the accountant rules on an unusual case, the answer is added to the table and the next similar bill is coded without a question. Over a few months the flagged share shrinks and the accountant's time goes to genuinely new situations.
What are common edge cases?
Edge cases decide whether the workflow is trusted. Bills in a foreign currency need the rate source recorded. Bills that mix standard-rated and exempt items need line-level coding, not one code for the whole bill. Credit notes reverse an earlier treatment and should point to the original bill. A supplier that registers mid-year changes how its earlier bills should be read. Capture each of these as a flag the agent raises, with a short reason, so the accountant sees why the bill was held. Review the flags quarterly: a flag that always ends in the same answer becomes a rule, and a rule that keeps being overridden gets removed.
Where KYN fits
KYN's own books take bills from Gmail, code them and queue them for approval, and a finance software startup's receipts, claims and GST product went to production in six weeks on Google Cloud. In each system, every action is logged with the actor, and filings wait for a named person. The agent proposes. The accountant decides.
The first 14 days go to reviewing your purchasing flow and sitting with the accountant who signs off your tax treatment. A full build ships in under 90 days. See finance systems.
Frequently asked questions
Can an agent file my GST return?
An agent can prepare the figures and a summary. We keep the filing with a named person, because the return is a declaration made in your company's name.
Does the agent know when a supplier is GST-registered?
It reads the number on the bill and checks the format. Confirming the number against the official register is a separate check, and a person should own the result for new suppliers.
What about bills in foreign currency?
The agent records the original currency and applies a rate from a source you choose, so each bill converts the same way every time. Your accountant confirms the rate policy matches what you use for the return.
Checked 30 October 2026.
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