Work stage 5 (detailed design) accounts for 25 percent of the fee. Whether it also took 25 percent of the effort is something most firms only find out once the project is finished. Until then, detailed design carries on, the client postpones the deadline, and the hours keep running against a fee whose share was fixed long ago. This is the blind spot that software for engineering firms has to close.
This is exactly where the margin of a planning firm is decided. It lies in the difference between the calculated fee share and the actual effort per work stage. Acquisition and fee calculation only set the framework. If you only see this difference in the final invoice, you calculate the next project with the same assumptions.
The economic data is clear. The member survey by the German Federal Chamber of Architects, the Federal Chamber of Engineers, AHO and VBI shows a median pre-tax return on sales of 12.0 percent for engineering firms in financial year 2024. At the same time, the share of firms with a pre-tax profit fell from 96.9 percent in 2023 to 84.2 percent in 2024. The overhead factor is 2.1. Every project hour that is not recorded or is assigned incorrectly therefore costs more than twice the hourly wage.
What this means at project level:
- Margin: with an overhead factor of 2.1 and a 12 percent return, a 10 percent overrun in work stage 5 is enough to wipe out the entire project result.
- Utilization: 75.5 percent of working time in engineering firms is project work. The remaining 24.5 percent has to be covered by project fees.
- Forecast: the average order backlog is 11.3 months. Without carrying plans forward across financial years, all planning ends on 31 December.
- Project costs: hourly rate changes at the turn of the year distort the post-calculation if the system does not version the historical rate.
- Resources: several technical disciplines work on the same building. Without separate budgets, you cannot say which discipline carries the project and which one weighs it down.
This comparison looks at five systems relevant to engineering and planning firms in Germany, Austria and Switzerland, from a commercial and project organisation perspective: work stages, billing, post-calculation and technical disciplines. CAD and BIM are not part of this comparison, as planning firms cover these tasks with their own specialist software.
HOAI 2021: what applies to fee calculation since the CJEU ruling
Since the First Ordinance amending the HOAI of 2 December 2020, a different logic applies to all contracts concluded after 31 December 2020. The HOAI is the German fee structure for architects and engineers (Honorarordnung für Architekten und Ingenieure). The trigger was the ruling of the Court of Justice of the European Union (CJEU) of 4 July 2019 in case C-377/17, which found the binding minimum and maximum rates to be in breach of the Services Directive.
The practical consequence is set out in § 2a HOAI: the fee tables show guideline values. Under § 7 HOAI, the fee is based on the agreement made in text form. If there is no such agreement, the base fee rate applies.
The work stage remains the level of calculation
The percentage weighting of the work stages for buildings and interiors is set out in § 34 (3) HOAI. For buildings: basic evaluation 2 percent, preliminary design 7, final design 15, approval planning 3, detailed design 25, preparation of contract award 10, assistance with contract award 4, construction supervision 32, project support 2.
Two stages therefore carry 57 percent of the fee. That is also where most of the effort risk lies. § 8 HOAI covers partial commissions: if not all work stages are commissioned, only the percentages of the commissioned stages may be charged.
It is worth noting that only 47.7 percent of engineering firms actually bill according to the HOAI. 37.3 percent bill by hours worked, 25.3 percent with a fixed fee. The work stage nevertheless remains the level of calculation, because it structures the service even when the fee was freely agreed. According to the 2026 business climate survey, 34 percent of engineering firms cite the non-binding nature of the HOAI as a strong or rather strong obstacle. Where the fee becomes negotiable, the pressure on post-calculation rises.
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Five criteria that decide software for engineering firms
1. Work stages as a native structure
Software for planning firms must treat work stages as a level of its own, against which hours are booked, planned and billed. In concrete terms: projects can be structured by work stage, hours are booked to the stage, and the fee share per stage is stored. Where this level is missing, a fee table in Excel reappears next to the system. The spreadsheet then becomes the real project management, and the system is just a time tracking system with a project field.
2. Billing by stage and billing status
Planning services are invoiced on completion or progress of individual stages. The system must track the billing status per stage, support partial invoices and recognise which fee share has already been invoiced. For change orders, the same structure must remain extendable without breaking the previous billing.
3. Long-running projects across financial years
A planning project often runs over several years, with breaks between stages in which the project is paused without being closed. The system must reflect these states, carry budgets forward across financial years and handle hourly rate changes at the turn of the year. Versioning is decisive here: an hour from 2024 must remain valued at the 2024 rate, otherwise every rate increase retroactively shifts the project result.
4. Technical disciplines with their own budget
Structural engineering, building services and electrical engineering work on the same building, with their own teams, their own rates and their own fee shares. Check whether disciplines can be managed as a separate structure within the project, with their own budget, their own billing type and their own analysis. The workaround via activity types delivers hours, but no contribution margins per discipline.
5. Use in Austria
Many German planning firms also work in Austria or employ staff there. This places requirements on working time law, public holiday calendars by federal state and collective agreement rules. Check whether the system comes with country-specific rule sets or whether they have to be configured.
The five systems compared
The following overview is based on the vendors' publicly documented information, retrieved on 21 October 2026. Features that a vendor does not list on its product pages are marked as not listed.
What the table says about the market
Three of the five systems manage HOAI work stages as a native structure. Clockodo and TimeTac describe on their own industry pages that work stages are mapped via the generic project or activity structure. That is clean time tracking, but the fee logic stays outside the system.
On the Austria criterion, the picture is reversed. TimeTac is the only vendor that explicitly states alignment with the Austrian Working Hours Act. Firms with locations in Germany and Austria therefore face a trade-off between fee logic and working time law, unless they choose a system that covers both countries' calendars via configurable rule sets.
Fee software or project software
When you search for HOAI software, Google mainly returns fee software: programs that calculate the fee according to the HOAI. These programs solve a different task from the systems compared here.
Fee software calculates what a project is allowed to cost. Project software shows what it actually costs and whether the calculated work stage matches the effort delivered. In many firms, both run side by side, with the fee calculation at the beginning and the post-calculation at the end. The break lies in between: the fee calculation ends up as a PDF in the project folder, the hours end up in a second system, and someone connects the two in Excel at the end of the quarter.
Where implementation fails in day-to-day office operations
The list of criteria can be ticked off in ten minutes. Implementation is difficult because it affects the day-to-day work of project management, accounting and office management at the same time.
Where time is lost
The fee calculation happens before the contract is awarded, often in a fee program or in an Excel file that has grown over time. After the award, someone sets the project up again in the time tracking system, this time with different names, a different stage structure and a rounded total budget. The fee table stays in the first document, the hours accumulate in the second.
For a project with four service profiles and six active work stages each, that is 24 items maintained twice. With the first change order, the maintenance starts all over again. Systems that convert the proposal into a project structure after the award eliminate this second pass entirely.
Where blind spots arise
The second blind spot lies in the running project. A work stage that exceeds its fee share does not report itself. It is noticed when project management checks on its own initiative, and that usually happens when something has already gone wrong.
A system solves this with thresholds: at 70, 90 and 100 percent of a stage's planned budget, a notification automatically goes to the project manager with budget responsibility, and if there is no reaction, to the head of department. The check runs with every time booking, at task and project level. This moves the point of realisation from the final invoice into the running stage, while change orders can still be negotiated.
Where profitability becomes invisible
The third point is post-calculation. 76.5 percent of working time is project work, the rest is overhead. Whether work stage 5 in the last project, with a 25 percent fee share, actually used 25 percent of the effort can only be answered if the hours were booked to the stage and the fee share is stored in the same system.
Firms that analyse this across three to five completed projects get a reliable answer to a question that otherwise remains a matter of experience: which work stages do we systematically under-calculate? In practice, these are often approval planning, whose 3 percent fee share does not hold up in complex procedures, and construction supervision, whose 32 percent is eaten up when construction is disrupted. 43 percent of engineering firms cite disrupted project workflows as a strong obstacle.
What a system must do to be accepted in daily work
The technically best solution fails if recording hours creates effort. Three points are decisive: booking must work on mobile devices and offline, because a considerable part of the work is done on the construction site. The stage selection must be pre-filtered so that only commissioned stages can be booked. And stages that have not been commissioned must be kept as inactive items, so that a later change order can be activated without setting anything up again.
From fee sheet to management basis
For firms that want to bring their fee calculation and project management together in one data basis, the handover point between proposal and project is the decisive moment. ZEP Operations covers this point with its integrated HOAI calculator.
In the proposal, you select the service profile by HOAI section, for example § 34 Buildings, § 51 Structural Engineering or § 56 Technical Equipment with the relevant system group. Several service profiles can be combined in one proposal, each with its own fee zone, fee rate and work stages. You enter eligible costs either directly or via the calculator with cost groups according to DIN 276. All 20 fee tables are stored, and intermediate values are interpolated linearly.
After the award, the stage structure including planning data is transferred to the project. From this point on, fee share and effort are in the same data record. Tasks carry their own planned hours, their own planned labour cost and their own billing type, so technical disciplines can be budgeted and billed separately. Overbooking protection and the three-level early warning apply at task and project level. For billing, payment plans with monthly, quarterly or annually recurring invoice items can be defined as early as project setup, and for public clients, the project-specific fields for tender number and object number are available in the XRechnung.
ZEP Operations costs €29 per user per month on an annual contract, €35 with monthly payment. The HOAI calculator, Proposals, Invoicing and Travel Expense Management are included from this line upwards. If you want to check whether your own service profile and stage structure can be mapped cleanly, recreate a completed project in the 14-day free trial. That tells you more than any feature list, because in this case the post-calculation has to deliver a known result.
Conclusion: how to reach a decision
Base your selection on three points that can each be checked in ten minutes in a demo.
- Have two service profiles set up: ask the vendor to set up a project with two service profiles and different fee zones. If a spreadsheet outside the system is needed for this, the firm pays for that spreadsheet every month in maintenance time.
- Recalculate a completed project: take a completed project from the last two years and recalculate it in the trial system. The question is whether the system can tell you, per work stage, how fee share and effort related to each other.
- Test the change order case: a work stage commissioned later must be possible to activate without setting up the previous billing again.
The answers to these three questions separate project software for planning firms from a time tracking system with a project field.
FAQs
Which software is suitable for HOAI billing in an engineering firm?
There are two groups to distinguish. Fee software calculates the fee according to the HOAI, the German fee structure for architects and engineers, and ends with the proposal. Project software books hours to work stages, bills by stage and analyses the effort per stage. For ongoing project work, the second group is what matters. Systems with an integrated HOAI calculator cover both, because the fee calculation flows directly into the project structure after the award. Three of the five systems compared here manage HOAI work stages as a native structure, two map them via generic project structures.
How do you do project controlling properly in an engineering firm?
What makes it special is the work stage as the controlling level. For buildings, the fee share per stage is fixed in § 34 (3) HOAI, while the effort is variable. Only comparing both figures per stage shows which stages are regularly under-calculated. In practice, this means hours are booked to the stage, not just the project, budgets are stored per stage, and thresholds report overruns while the stage is still running. Across three to five completed projects, this gives you a reliable basis for the next calculation.
How much does software for engineering and planning firms cost?
The list prices of the systems compared here range from around €9.50 to €39 per user per month. What determines the total cost are the additional items: some vendors also charge a monthly base fee per office of €60 to €160, others separate hosting and support packages or one-off setup fees. Systems with integrated HOAI functionality are usually found in the higher product lines. ZEP Operations, with HOAI calculator, Proposals and Invoicing, costs €29 per user per month on an annual contract.
Does a planning firm need separate commercial software in addition to CAD?
Yes. CAD and BIM systems produce the design, but they do not manage hours, fees or post-calculation. Both kinds of system sit side by side and serve different purposes. The commercial side decides the margin, because that is where the relationship between fee share and effort becomes visible. According to the 2025 professional survey by the German Federal Chamber of Architects, rising software costs from mandatory subscription models already weigh heavily on firms, which makes the question of how many parallel systems to run even more pressing.
How do you bill work stages correctly on multi-year projects?
Three requirements must be met. First, the billing status must be tracked per stage so that you can see which fee share has already been invoiced. Second, budgets must be carried forward across financial years, because the average order backlog in engineering firms is more than eleven months and projects are regularly paused. Third, hourly rates must be versioned over time, so that a rate increase at the turn of the year does not retroactively change the valuation of hours already worked and distort the post-calculation.
Is the HOAI still binding in 2026?
The HOAI still applies, but its fee tables have no longer been binding since the amending ordinance of 2 December 2020. § 2a HOAI describes the table values as guideline values. Under § 7 HOAI, the fee is based on the agreement made in text form; if there is no agreement, the base fee rate applies. The trigger was the CJEU ruling of 4 July 2019 in case C-377/17. The rule applies to all contracts concluded after 31 December 2020. 34 percent of engineering firms see the non-binding nature as a strong obstacle.
