--- updatedAt: 2026-07-21T08:00:49.000Z agentTools: projectIndex: https://docs.fonoa.com/llms.txt --- # Update a Calculation ## Committing Calculations Once a calculation results in a sale, you can update the status of a calculation to `committed` by sending an HTTP `POST` to `https://api.fonoa.com/tax/v2/calculations//commit` with a body containing: ```json Commit Request { "timestamp": "2026-01-15T20:48:59.000Z", } ``` On receipt, the API will respond with an HTTP `202 Accepted`, and an empty response body. Committing a calculation will update its status and include it for revenue tracking if applicable. ### Listen for a webhook Once a commit has been processed, a webhook notification will be sent to the URL set during the onboarding process. Webhooks have the same payload across the Fonoa platform. More info about it can be found [here](https://docs.fonoa.com/reference/webhooks). Here’s an example payload you will receive from us. ```json Webhook Payload Content-Type: application/json Fonoa-Webhook-Token: eyJhbGciOiJSUzI1NiI...QdRA (See webhooks documentation) { "webhook_id": "875bd24499d303cbe8afb3db1987d8aa522d63bb", "event_type": "tax.calculation_committed", "delivered_at": "2066-01-02T15:04:05Z", "resource_id": "1010b4d8-9361-4a7e-98cc-9419dbba695c", "resource_url": "https://api.fonoa.com/tax/v2/calculations/1010b4d8-9361-4a7e-98cc-9419dbba695c" } ``` The `resource_id` field will contain the `id` of the calculation. The calculation can be accessed using the `GET` endpoint in `resource_url`. ### Do not use the `resource_id` to construct URLs. Always use the `resource_url`. If the commit was successful, the `status` of the calculation will now have changed to `committed`: ```json GET Response { "data": { "uuid": "1010b4d8-9361-4a7e-98cc-9419dbba695c", "status": "committed", "input": { "supplier": { "taxable": true, "country": "gb" }, "customer": { "taxable": false, "country": "nl" }, "transaction": { "price_includes_tax": false, "date": "2026-01-14T20:48:59.000Z", "items": [ { "id": "34db79d1-24bf-4c22-863e-1f7832f24be3", "unit_price": 100, "tax_category_code": "fs_0503010000", "quantity": 1 } ] } }, "output": { "id": "1010b4d8-9361-4a7e-98cc-9419dbba695c", "result": { "total_gross": 121, "total_net": 100, "total_indirect_tax_amount": 21, "items": [ { "id": "34db79d1-24bf-4c22-863e-1f7832f24be3", "gross_amount": 121, "net_amount": 100, "indirect_tax_amount": 21, "effective_indirect_tax_rate": 0.21, "tax_breakdown": [ { "country": "nl", "country_name": "Netherlands", "rate_class": "s", "tax_level": "federal", "name": "BTW", "rate": 0.21, "amount": 21 } ] } ] } } } } ``` ## Reverting Calculations A committed calculation can be reverted by sending an HTTP `POST` to `https://api.fonoa.com/tax/v2/calculations//revert` with a body containing: ```json Revert Request { "timestamp": "2026-01-16T20:48:59.000Z", } ``` On receipt, the API will response with an HTTP `202 Accepted` and an empty response body. Reverting a calculation will change its status to `reverted` and remove it from revenue tracking if previously included ### Listen for a webhook Similar to a commit, a webhook notification will be sent to the URL configured during onboarding after the revert has been processed: ```json Webhook Payload Content-Type: application/json Fonoa-Webhook-Token: eyJhbGciOiJSUzI1NiI...QdRA (See webhooks documentation) { "webhook_id": "875bd24499d303cbe8afb3db1987d8aa522d63bb", "event_type": "tax.calculation_reverted", "delivered_at": "2066-01-02T15:04:05Z", "resource_id": "1010b4d8-9361-4a7e-98cc-9419dbba695c", "resource_url": "https://api.fonoa.com/tax/v2/calculations/1010b4d8-9361-4a7e-98cc-9419dbba695c" } ``` ## Errors If there is an error during the processing of a commit or a revert, a webhook notification will be sent to the URL configured during onboarding: ```json Webhook Payload (on error) Content-Type: application/json Fonoa-Webhook-Token: eyJhbGciOiJSUzI1NiI...QdRA (See webhooks documentation) { "webhook_id": "875bd24499d303cbe8afb3db1987d8aa522d63bb", "event_type": "tax.calculation_commit_failed", "delivered_at": "2066-01-02T15:04:05Z", "resource_id": "1010b4d8-9361-4a7e-98cc-9419dbba695c", "resource_url": "https://api.fonoa.com/tax/v2/calculations/1010b4d8-9361-4a7e-98cc-9419dbba695c", "errors": [ { "code": "INVALID_COMMIT_TIMESTAMP", "message": "The commit timestamp has to be on or after the transaction.date of the calculation" } ] } ``` An `errors` field indicates that the commit/revert was **unsuccessfully processed**, and will have to be retried after fixing the issue ## How updates are processed All updates to a calculation are processed in the order of the `timestamp` sent in the body of the `POST`, regardless of the order in which they are submitted. ### Can the client submit multiple commits/reverts? Yes. All commits will be accepted and applied in the order of `timestamp`. > **Note**: Only the first commit will include the calculation in revenue tracking; subsequent commits will have no effect on revenue. ### Can a reverted calculation be committed again? Yes, `reverted` is not a final status. Submitting a commit for a reverted calculation will change its status back to `committed` ### How are two updates with the same timestamp processed? Updates with identical `timestamp` values in the body will be processed in the order that the client submitted them ### Can a calculation be marked as committed during the initial submission? Yes. Clients can set the `transaction.commit` field to `true` in the request body of the HTTP `POST` to . This will save the calculation with the status of `committed` and include the calculation in revenue tracking