Projects · Case study

From the first quotation to the final invoice.

How a construction group unified the quotation, contract and invoicing processes of all its subsidiaries in one system.

IndustryConstruction and Real Estate
Deliveryaround nine months
ReplacementLegacy systems migrated
CoreDocument templates, billing, e-invoicing

How it works

Entered once, used everywhere.

A construction project produces many documents over its lifetime. The data behind them is entered once and carried forward.

  1. 01Cost estimate
  2. 02Quotation
  3. 03Contract
  4. 04Change order
  5. 05Progress invoices
  6. 06Final invoice
01 / 06

Cost estimate

Items are created once in the bill of quantities, via GAEB import if required. This produces the cost estimate.

02 / 06

Quotation

The cost estimate becomes the quotation. The items are retained, and the template adds the client and project automatically.

03 / 06

Contract

Once the order is placed, the quotation becomes the contract, together with the payment schedule for the instalments.

04 / 06

Change order

If additional work is added, a change order is created. The contract value grows with it, and nothing is entered twice.

05 / 06

Progress invoices

A progress invoice is created with one click for each instalment in the payment schedule.

06 / 06

Final invoice

The final invoice offsets all progress payments made. It is issued as an e-invoice and filed in the client's DMS.

Scroll to see the next step.

Cost estimateQuotationContractChange order CO1Progress invoicesFinal invoiceCE-2026-017QUO-2026-0142C-2026-0142to contract C-2026-0142FI-2026-0031
ClientWohnbau Nord GmbHProjectLindenhof Residential Quarter, Building B

Bill of quantities

01Earthworks€84,200.00
02Shell construction€612,500.00
03Roofing and waterproofing€146,800.00
04Windows and doors€98,400.00
CO1Additional basement waterproofing€23,600.00
Net totalQuotation totalContract valueNew contract value€941,900.00€941,900.00 €965,500.00€965,500.00

Progress invoices

PI-2026-001Instalment 1 · 30%€282,570.00
PI-2026-002Instalment 2 · 30%€282,570.00
PI-2026-003Instalment 3 · 30%€282,570.00
Total work including change order CO1€965,500.00
less progress invoices 1 to 3− €847,710.00
Balance due, net€117,790.00

Payment schedule

Instalment 410%
E-invoice · ZUGFeRD✓ filed in DMS

Illustration with sample data. Companies, project and amounts are fictitious.

Starting point

Each subsidiary of a property developer used its own solutions for quotations, contracts and invoices. Documents looked different depending on the company, data had to be maintained several times over, and there was no shared overview of the commercial status of projects.

On top of this came e-invoicing: in future, invoices were to be issued in the European standard, and in every company.

Goal

One shared system for all companies that covers the full commercial side of a construction project, without losing existing quotations, contracts and invoices.

Approach

We started with several requirements workshops with the client: which documents exist, which types of contract, and how does each company invoice today? This produced a shared picture of the processes before the first line of code was written.

From this we developed the concept and the architecture and built the application in stages, from the bill of quantities through quotation and contract to billing. The client was able to try out each stage early, and their feedback went straight into the next one. The final step was migrating the existing data and switching over.

Solution

  • Multi-tenant. Every company works in the same system, with its own data, its own templates and its own corporate design.
  • Template editor. The client creates document templates for every type of contract and every use case themselves. Placeholders are filled automatically with the values from the project when a document is created.
  • Bills of quantities in industry-standard formats. Items can be imported and exported in the common GAEB formats, so exchanging data with architects, engineers and subcontractors works as before.

Migration

New software is only as good as the switchover. We analysed the data from the subsidiaries' previous systems, cleansed it and transferred it to the new system.

Existing quotations, contracts and invoices remain available there. All new documents are created in the new system.

Result

  • One system instead of standalone solutions. All companies follow the same process, and the previous solutions have been replaced.
  • The business department maintains templates itself. New types of contract or revised wording need no programming.
  • Growth without a new system. A new company is set up as a tenant and can start working straight away.
  • Ready for e-invoicing. Invoices are issued in line with the European standard EN 16931 and filed automatically in the client's document management system.

Technologies

ZUGFeRDGAEBJavaScriptNode.jsVue.jsAWS

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