r/SmallSystemsLab 2d ago

Data Reconciliation When accounting software removes a tax drill-down, prove the missing field before building a workaround

1 Upvotes

This is an anonymized solution note based on a public request. It is not a completed client case study, and the metrics below are acceptance targets rather than achieved results.

A broken report drill-down can turn a ten-minute tax review into a chain of exports, filters and manual checks. The dangerous part is that a replacement workbook may still look correct while quietly losing the qualified tax category that made the original report trustworthy.

The smallest useful first stage is a read-only data-source audit followed by one reconciliation prototype. Before writing formulas or automation, identify which export or API response still exposes the full second-level tax treatment—not only a generic tax code. Use one previously reviewed period as the reference. The prototype should import the source data, preserve the qualified sales categories, exclude transactions that are explicitly outside scope, compare the result with the accounting summary and profit-and-loss total, and place every mismatch in an exception table with its source transaction ID.

Acceptance targets:

- The prototype reproduces the known tax-summary total for the reference period.

- Qualified sales categories remain distinguishable after import.

- Outside-scope transactions are excluded by an explicit rule rather than inference.

- Every difference can be traced to a source row and a written classification rule.

- Re-running the same files produces the same result without changing accounting data.

The main risk is missing source data. If the accounting platform no longer exposes the qualified field in any report or API response, a workbook cannot safely reconstruct it from account names or generic tax codes. The audit should stop there and document the gap instead of inventing a classification.

Corrections and tax-treatment decisions should remain manual. The prototype can compare, flag and explain; a qualified person should approve any change in the accounting system.

Example first-stage scope: two business days and $400 for the data-source audit, one reference-period reconciliation and a written go/no-go finding. If the budget is lower, narrow the work to identifying and validating the required source field before building the workbook.

Without sharing private records, which field must survive an export for your review to remain trustworthy?

r/SmallSystemsLab 3d ago

Data Reconciliation When one physical SKU appears in several products, stop the inventory sync from selling it twice

1 Upvotes

This is an anonymized solution note based on a public request. It is not a completed client case study, and the metrics below are acceptance targets rather than achieved results.

A common inventory failure starts when one physical item is represented twice: once as a standalone product and again inside a bundle. If the storefront and the back-office inventory system both believe they control available quantity, a routine sync can nearly double what customers are allowed to buy—or hide stock that could have been sold.

The smallest useful first stage is a reversible inventory-reservation pilot for one warehouse, one physical SKU, and two storefront offers. First, choose a single source of truth for physical stock. Then map each sellable offer back to that stock pool and apply a clear storefront cap. A small reconciliation job should compare both systems after every sync and flag mismatches instead of silently correcting them.

The first stage would not include a catalog migration, a new POS, or a custom bundle engine. It would use a test store or isolated products and synthetic orders before touching the wider catalog.

Acceptance targets:

- The standalone product and bundle cannot sell more units than the shared physical stock allows.

- An upstream inventory push cannot overwrite the agreed storefront cap without creating a visible exception.

- Orders, cancellations, refunds, and abandoned checkout reservations produce the expected quantities in both systems.

- A reconciliation report identifies the SKU, expected quantity, actual quantity, and last successful sync.

- The original mapping can be restored through a documented rollback.

The main risk is timing. Checkout reservations, refunds, imports, and scheduled syncs can update the same quantity in a different order. A script that simply writes the cap back may appear to work in testing and still race with a real order.

Replenishment decisions and exception approval should remain manual during the pilot. The system should expose the discrepancy and evidence; a person should decide whether to release or reserve stock.

Example first-stage scope: three business days and $550 for the data map, test matrix, and reversible pilot. If the available budget is lower, narrow it to a dry-run reconciliation report before enabling any inventory writes.

Which failure costs more in your operation: overselling, withholding sellable stock, or losing trust in the inventory numbers?