The expressions above read these as $const. They are the figures the annual refresh replaces, so they live as data rather than being written into the formulas — which is what makes a year-on-year change a one-line diff instead of an edit to arithmetic.
Constant
Value
standardRate
0.09
registrationThreshold
1000000
Test vectors (5)
Every case is executed against this model on each build, by the Java engine and independently by a JavaScript one. A mismatch of a single cent fails the build, so the page cannot ship advertising a figure the model no longer produces.
Case 1 — S1 100.00 SGD net at 9%
given amount
100
given direction
add
given reverseCharge
no
given annualTurnover
0
expect vatAmount
9
expect grossAmount
109
expect netAmount
100
Case 2 — S2 109.00 SGD gross back to net
given amount
109
given direction
remove
given reverseCharge
no
given annualTurnover
0
expect netAmount
100
expect vatAmount
9
Case 3 — S3 reverse charge: the supplier charges no GST
given amount
100
given direction
add
given reverseCharge
yes
given annualTurnover
0
expect vatAmount
0
expect grossAmount
100
Case 4 — S4 taxable supplies over SGD 1 million: registration required
The whole model as JSON — inputs, outputs, formulas, vectors and sources in one re-runnable document.
This model is published under CC BY 4.0: use it, adapt it, build on it, with attribution. The licence covers the model — the expression of each rule and the arrangement of the catalog. The rates and thresholds are law, and nobody licenses those; the sources above are where they come from.