Invoicing at the customer's premises, on a handheld device, offline, with correct tax and customer-specific pricing, is harder than it looks. It is also the feature that separates route accounting products from delivery apps.
What has to happen at the stop
In perhaps ninety seconds:
- Identify the customer and pull their contract terms
- Capture what is actually being delivered or sold, with any changes
- Apply customer-specific pricing and active promotions
- Handle returns and credits from the same visit
- Calculate tax correctly for the jurisdiction and product
- Produce a compliant invoice document
- Capture signature or other proof
- Record payment if collected
- Store everything locally and sync when possible
Any of those failing at the stop means a phone call to the office, a delayed vehicle and an unhappy customer.
Offline is a hard requirement
Not a nice-to-have. Signal fails in industrial estates, basements, rural areas and inside buildings — which is where most deliveries happen.
Offline-capable means:
- The full catalogue, price lists and customer data are cached on the device before the shift.
- Invoices are generated locally, including document numbering, with a strategy that avoids collisions.
- Tax rates are cached and versioned.
- Sync is resilient — partial sync, interrupted sync and duplicate submission must all be handled.
- Conflicts are resolvable — if the office changed a price mid-day, the system needs a defined rule about which wins.
Document numbering deserves attention. Sequential numbering per device, per route, or centrally reserved blocks are all workable; unmanaged central sequencing is not, because it requires connectivity at the moment of issue. Some jurisdictions constrain the numbering scheme legally, so confirm before designing.
Pricing at the point of sale
The device must resolve the price the same way the back office would. Typical layers:
| Layer | Example |
|---|---|
| Base price list | Standard trade price |
| Customer price list | Negotiated group price |
| Contract price | Specific SKU price for this customer |
| Volume break | Price per case above a threshold |
| Promotion | Temporary price reduction, active this week |
| Deal | Buy 10 get 1 free |
| Manual override | Within authority limit, reason coded |
Getting this wrong produces invoices that must be credited and reissued — expensive, and corrosive of customer trust. Test with your most complicated customers, not with a clean sample. See pricing and promotions.
Tax
Tax at the point of sale is the most jurisdiction-specific part of the system.
- Rate determination by product category, customer type and location. In some countries the delivery address determines the rate.
- Exemptions — resale certificates, charity status, export.
- Deposits on returnable containers, often taxed differently from the product.
- Rounding rules, which differ by country and can produce penny discrepancies that finance will not tolerate.
- Invoice content requirements — many jurisdictions specify mandatory fields, sequential numbering and retention rules.
- Electronic invoicing mandates, which now apply in a growing number of countries and often require submission to a government platform in a defined format.
That last point is changing quickly. If you operate in a country with mandatory e-invoicing or where it is being introduced, make it a scored requirement rather than a footnote, and ask for the vendor's compliance roadmap in writing.
Printing and delivery of the document
Options, in rough order of preference:
- Email or portal delivery — cheapest, most reliable, easiest to archive.
- Bluetooth mobile printer — still required by many trade customers who want paper at the door.
- Vehicle-mounted printer — heavier duty, common in high-volume DSD.
- In-cab tablet display with signature and later document delivery.
Mobile printers are a persistent source of field support calls: pairing failures, paper, battery, driver frustration. Standardise on one model, carry spares, and treat printer support as a real operational cost.
Credits and returns
Handled at the same visit, or you create a reconciliation problem:
- Credit against a specific original invoice where possible, for traceability
- Reason codes on every credit line
- Authority limits with escalation
- Physical stock movement recorded at the same time
- Immediate visibility to the office, since credits are a classic control weakness
Questions readers send us
Can we invoice from the back office instead of at the stop? Yes, and many operations do — it simplifies the device and avoids offline complications. The trade-off is losing on-the-spot accuracy, immediate payment collection and the customer's signature against the priced document, which increases disputes.
What happens if the device fails mid-route? There must be a documented fallback: pre-printed manual invoice books with controlled numbering, entered into the system on return. Every route accounting operation needs this and most discover it during their first device failure.
How do we handle a customer who disputes the price at the door? Allow a controlled override with a reason code and an authority limit, then report every override. Prohibiting overrides entirely leads to refused deliveries and drivers agreeing verbal side deals the system never sees.
Do mobile invoices satisfy legal requirements? In most jurisdictions yes, provided content, numbering and retention rules are met — but requirements vary and are tightening with e-invoicing mandates. Confirm with your accountant for each country in which you operate before go-live.
How long should invoices be retained on the device? Long enough for the driver to reference recent visits, typically 30–90 days, with the authoritative archive held centrally. Devices are lost, stolen and broken; they should never be the only copy of a financial record.
