Billing an architect's mandate in Switzerland: between SIA standards and contract law
The Swiss independent architect operates in one of the country's most codified professional frameworks. Their activity is governed simultaneously by the Swiss Code of Obligations (art. 394 et seq. CO on mandates, art. 363 et seq. CO on work contracts depending on scope), by the SIA regulations that are referenced in nearly 100% of contracts, and by the registration conditions of the Swiss Register of Architects (REG) or the Swiss Society of Engineers and Architects (SIA). Billing a mandate therefore requires mastery not only of the QR-invoice and mandatory mentions, but also of the calculation of the determining construction cost, the allocation of fees by phase, and the practices specific to architectural competitions.
This guide is aimed at independent architects, small offices organized as LLCs or SAs, and recent graduates in the process of setting up. It covers SIA 102 and 103 pricing, invoicing by mandate phase, the 8.1% VAT, ancillary costs, and the specifics of competitions. The goal: to produce a fee statement that is technically defensible, compliant with SIA regulations, and convincing both for a private client and for a public authority.
1. The independent architecture market in Switzerland
Common legal structures
Three forms of practice dominate Swiss architectural practice:
- Sole proprietorship (RI): the architect operates under their own name with unlimited personal liability. The simplest status to set up, suited to solos and practitioners starting out. Billing is issued in the architect's name with their UID, and VAT number if VAT-registered.
- Architecture office as an LLC (Sàrl/GmbH): a legal entity with a minimum capital of CHF 20,000 and liability limited to contributions. Now the majority form for offices of 2 to 10 employees. The LLC issues invoices, not the architect personally.
- Joint-stock company (SA/AG): minimum capital of CHF 100,000. Reserved for established offices, multi-partner partnerships and structures that bid for major public mandates requiring financial strength.
- Office consortium: for a specific mandate, several offices team up in a simple partnership (art. 530 CO). One of the offices is designated as contract lead for billing purposes.
The choice of status directly impacts invoicing and taxation. See our comparison sole proprietorship or LLC in Switzerland for a detailed assessment.
REG registration: architect A or B
The Register of Architects (REG) is the Confederation-recognized foundation that keeps the register of qualified professionals. Two main levels:
| Level | Qualification | Practical scope |
|---|---|---|
| REG A | Master in architecture + 3 years of supervised practice | Access to major mandates, public competitions, full technical responsibility |
| REG B | Bachelor's or equivalent UAS + 5 years of practice | Common mandates, site supervision, building permits in most cantons |
REG registration is not mandatory to practice across all cantons, but several cantons (notably Vaud, Geneva, Ticino) condition the signature of plans submitted to the municipality on registration. Many private clients and all public procurement also require it. Always indicate your REG number on the fee statement: it is a mark of credibility and evidence of qualification.
SIA membership
Joining SIA as an individual member or as an office is voluntary but highly recommended. It allows in particular:
- The direct contractual application of SIA regulations (notably SIA 102 for architect's services and fees).
- Access to the commented case law of the SIA Commission for architects' contracts.
- Participation in competitions organized under SIA Regulation 142.
- Basic professional liability coverage via SIA partnerships.
Referring to SIA regulations in the architect's contract creates a clear normative framework that a judge will apply in the event of a dispute over remuneration.
2. Fee calculation under SIA 102, 103 and 108
The three reference regulations
| Regulation | Scope |
|---|---|
| SIA 102 | Services and fees of the architect |
| SIA 103 | Services and fees of the civil engineer |
| SIA 108 | Services and fees of the building services engineer (HVAC, plumbing, electrical) |
SIA 102 is the central document for any architect invoicing using the normative method. It defines the phases of the mandate, ordinary and extraordinary services, and the formula for calculating fees based on the determining construction cost.
The determining construction cost (DCC)
The determining construction cost (DCC) is the basis for fee calculation. It corresponds to the total construction cost excluding VAT, adjusted by the architect's services (excluding taxes, excluding land, excluding loose furniture). The DCC is expressed in CHF ex. VAT. For a detached villa project at CHF 1.5 million ex. VAT in construction cost, the DCC is typically around CHF 1.3 to 1.4 million after deducting non-determining items.
The DCC notably includes:
- Structural works 1 and 2 (BCC 2).
- Technical installations (partial BCC 2 and BCC 3, with weighting).
- Interior fittings (BCC 2).
- Certain proportional secondary costs.
It typically excludes:
- Land and property taxes.
- The fees themselves.
- Loose furniture and equipment not fixed to the building.
- Exterior landscaping work beyond a certain percentage.
The SIA formula: h × B × q × r
The architect's base fees are calculated using the SIA 102 formula:
Fees = h × B × q × r × (1 + s)
where:
- h: calculated base value of fees, a function of the DCC (SIA logarithmic formula). The higher the DCC, the greater h in absolute value, but the lower the ratio (h/DCC) becomes (economies of scale).
- B: difficulty factor (building class coefficient, generally between 0.9 for a simple building and 1.2 for a complex work).
- q: percentage of quality or share of services. A full mandate covering all phases gives q = 100%.
- r: adjustment factor for repetitive services or particular constraints (often 1.0).
- s: negotiated surcharge (often 0, possibly positive for exceptional constraints).
In 2026 practice, the fees/DCC ratio typically falls within these orders of magnitude:
| DCC (CHF ex. VAT) | Indicative total fee rate | Expected fees |
|---|---|---|
| 500,000 | 14 to 16% | CHF 70,000 to 80,000 |
| 1,000,000 | 12 to 14% | CHF 120,000 to 140,000 |
| 2,000,000 | 10 to 12% | CHF 200,000 to 240,000 |
| 5,000,000 | 9 to 10% | CHF 450,000 to 500,000 |
| 10,000,000 | 7.5 to 9% | CHF 750,000 to 900,000 |
These values are indicative and depend on the B difficulty factor, the q scope of services and the level of negotiated adjustment. For a specific project, a formal calculation using the SIA spreadsheet is essential.
SIA 102 mandate phases
The architect's full mandate is broken down into eleven partial phases grouped into six main phases:
| Phase | Designation | % of base fees |
|---|---|---|
| 1 | Definition of objectives | 2% |
| 2 | Preliminary studies | 7% |
| 3 | Project study (preliminary design, project, permit application procedure) | 21% |
| 4 | Tendering (specifications, submission, award) | 18% |
| 5 | Execution (execution project, construction, commissioning) | 50% |
| 6 | Management (operation, warranty) | 2% |
Total: 100% for a full mandate. An architect mandated only for phase 3 (preliminary design and permit application) will receive 21% of the total fees calculated under the SIA formula.
Complete numerical example
Project: 8-unit residential building, DCC CHF 2,000,000 ex. VAT, average building class (B = 1.0), full mandate (q = 100%).
- Calculated base value h (according to SIA logarithmic formula) ≈ CHF 210,000.
- Total fees ≈ 210,000 × 1.0 × 100% × 1.0 = CHF 210,000 ex. VAT.
- Breakdown by phase:
- Phase 1 (definition): CHF 4,200
- Phase 2 (preliminary studies): CHF 14,700
- Phase 3 (project): CHF 44,100
- Phase 4 (tendering): CHF 37,800
- Phase 5 (execution): CHF 105,000
- Phase 6 (management): CHF 4,200
Invoicing follows this breakdown in successive stages, as detailed in section 4.
3. Time-based or lump-sum invoicing under SIA
The SIA 102 architect's contract
The standard SIA 102 contract provides for three modes of remuneration, which can be combined:
- Remuneration based on the DCC (normative method described above).
- Time-based remuneration at an agreed hourly rate.
- Lump-sum remuneration on the basis of a globally negotiated amount.
The contract must explicitly specify the chosen mode; otherwise the DCC method applies by default under practices recognized by SIA.
2026 hourly rate: CHF 120 to 200/h
SIA Regulation 102 publishes each year a range of indicative hourly rates by collaborator category. The 2026 customary rates for private practice fall within these orders of magnitude:
| Category | Indicative hourly rate (CHF ex. VAT) |
|---|---|
| Associate architect / experienced project manager | 170 to 220 |
| Qualified architect (≥ 5 years of practice) | 140 to 180 |
| Junior architect (recent graduate) | 120 to 150 |
| Architectural draftsperson | 100 to 130 |
| Intern / apprentice | 60 to 90 |
Rates vary significantly by canton. Geneva and Zurich are in the upper part of the ranges, while Valais, Jura or some rural German-speaking regions apply more contained rates. The fee statement must indicate hours per category and the rate applied, to allow verification by the client.
Advantages and limitations of each mode
| Mode | Advantages | Disadvantages |
|---|---|---|
| DCC (SIA normative) | Predictability, solid legal framework, accepted by liability insurers | Poorly suited to partial assignments or feasibility studies |
| Time-based | Flexible, covers the unforeseen, suited to study phases | Unpredictable for the client, requires rigorous time tracking |
| Lump-sum | Maximum clarity for the client, commercial security | Financial risk in case of underestimation, poorly suited to evolving projects |
Current practice often combines all three: lump-sum or DCC for phases 3 to 5, time-based for extraordinary services (expert reports, coordination with specialists, steps not covered by the contract).
4. QR-invoice for architects: phase-based billing
Why the QR-invoice is essential
Since 30 September 2022, the QR-invoice has been the only payment slip format accepted in Switzerland. For an architect billing high amounts in installments, the QR-invoice enables:
- A unique QRR reference per statement, avoiding any confusion between advance, interim statements and final balance.
- Automatic bank reconciliation by project in the office's analytical accounting.
- Payment scannable by the client from their e-banking in seconds.
Initial retainer upon signing
The initial retainer is a standard practice in architecture, particularly for preliminary study and project mandates. SIA practices recommend a retainer corresponding approximately to phase 1 and part of phase 2 (around 5 to 10% of estimated total fees). This retainer covers the first studies before final validation of the mandate by the client.
The retainer invoice is issued upon signing the contract, with a separate QR-invoice. It carries 8.1% VAT if the office is VAT-registered.
Interim statements by phase
For a full mandate, billing typically follows SIA milestones:
| Time | Document | Calculation basis |
|---|---|---|
| Signing | Retainer invoice | 5 to 10% of estimated fees |
| End of phase 2 | Statement no. 1 | Phases 1 + 2, i.e. 9% of total |
| End of phase 3 | Statement no. 2 | Phase 3, i.e. additional 21% |
| Award (end of phase 4) | Statement no. 3 | Phase 4, i.e. additional 18% |
| Monthly statements during phase 5 | Site progress statements | Phase 5 prorated with works, 50% total |
| Acceptance of the work | Final statement | Balance, including phase 6 |
Each interim statement presents:
- The total amount of agreed fees.
- The percentage of progress of services at the date of the statement.
- The cumulative amount billed (retainer + previous statements).
- The amount to be paid for the current statement.
- The VAT applied.
- Any disbursements or ancillary costs rebilled.
Balance upon acceptance
The last invoice, called the final statement, presents the balance of fees, integrates phase 6 (management and warranty) and regularizes any DCC adjustments observed at the end of the works. It is generally issued after acceptance of the work and commissioning.
If warranty works extend beyond, phase 6 can be billed separately (post-acceptance statement at the 12th or 24th month depending on the contract). See our Swiss invoice template for mandatory mentions applicable to each statement.
5. VAT for architects
Standard 8.1% rate
Architectural services are subject to the standard VAT rate of 8.1% since 1 January 2024. This rate applies to all services: studies, plans, construction management, expert reports, rebilled ancillary costs (color plans, models, travel). There is no reduced rate applicable to architecture, regardless of the type of work (housing, public facility, renovation).
See our complete 2026 VAT guide for the full rate schedule and special cases.
CHF 100,000 registration threshold
Any architect whose worldwide turnover exceeds CHF 100,000 over 12 rolling months must register for VAT within 30 days. Below this threshold, registration is optional.
In practice, a full-time independent architect almost systematically reaches this threshold by the second year. Voluntary registration is often relevant from the first year, as it allows input VAT deduction on software (Archicad, Revit, Rhino), IT equipment, entertainment expenses and office rental. See our VAT guide for freelancers.
Effective method or net tax rate
| Method | Frequency | Principle | Relevance for architects |
|---|---|---|---|
| Effective | Quarterly | VAT collected − input VAT | Offices with significant software or real-estate investments |
| Net tax rate | Semi-annually | Flat rate on VAT-inclusive turnover (specific architects rate around 6.2%) | Solo offices with low input VAT load |
Most architecture offices benefit from the effective method as soon as software and technical subcontracting costs represent a significant share. The comparative calculation should be done annually with the accountant. See our VAT declaration guide.
Cross-border projects and foreign clients
Two typical cases:
- Work located in Switzerland for a foreign client: Swiss VAT at 8.1% due by the Swiss architect. The client's domicile does not matter.
- Work located abroad (French second home, villa in Spain): services related to a property follow the location of the property (art. 8 para. 2 let. f VAT Act). The Swiss architect invoices without Swiss VAT, but may be liable for local VAT under the rule of the country of location.
- Swiss client for work in Switzerland with foreign subcontracting: acquisition of services abroad can trigger acquisition taxation (VAT reverse charge).
Cross-border VAT registration is technically complex: always consult a specialized accountant for international mandates.
6. Retainers, liability and warranties
Preliminary study retainer
The retainer upon signing is a well-established practice in Swiss architecture. It typically corresponds to coverage of phases 1 and 2 (definition of objectives and preliminary studies), i.e. 9% of the full mandate. For a project with forecast fees of CHF 200,000, a retainer of CHF 18,000 ex. VAT upon signing secures the start of the mandate.
This retainer is deducted from the first interim statement (statement no. 1 at the end of phase 2). It remains acquired by the architect if the client renounces the project after preliminary studies, to cover the work already performed.
Warranty retention in architecture
Unlike craftsmanship (see our article on Swiss artisan invoicing), warranty retention on architect's fees is rarely used. The architect's remuneration covers an intellectual service and not a physical work: there are no hidden defects in the classic sense.
Some public or institutional clients nevertheless impose a retention of 3 to 5% released after a period of 1 to 2 years post-acceptance, to cover any corrections related to design errors. This clause must be explicitly provided in the contract; failing that, SIA 102 does not provide for it.
Professional liability insurance
Art. 1.4 of SIA Regulation 102 requires the architect to subscribe to professional liability insurance adapted to the size and nature of the mandates. The annual premium typically varies from:
- CHF 1,500 to 3,000 for a solo architect with turnover below CHF 300,000.
- CHF 3,000 to 8,000 for an office of 2 to 5 employees.
- Above CHF 10,000 for structured offices and sensitive public mandates.
The recommended minimum coverage is CHF 5 million per claim, to be raised to CHF 10 million for public mandates or high-value works. An explicit mention on the contract and an attached certificate reassure clients and speed up signing. See our complete insurance guide for freelancers.
Planner's liability
Beyond classic liability, the architect is exposed to contractual liability (art. 398 CO, mandate) and can be jointly liable with executing companies for certain poorly controlled execution defects (default of construction management). Federal case law has consolidated this liability in several recent rulings, reinforcing the importance of a rigorous acceptance report and traceability of decisions taken in phase 5.
7. Architectural competitions
SIA Regulation 142
Swiss architectural competitions are governed by SIA Regulation 142 (regulation on architecture and engineering competitions) which sets:
- Competition categories (open, selective, by invitation).
- Minimum indemnities for participants.
- Jury composition rules.
- Client obligations (awarding the mandate to the winner, awarding subsequent phases).
Competition fees and indemnities
The competition indemnity is a lump sum paid to participants who submit a compliant dossier. Customary 2026 amounts:
| Type of competition | Indemnity per participant (order of magnitude) |
|---|---|
| Ideas competition | CHF 5,000 to 15,000 ex. VAT |
| Project competition (selective, 5 to 8 offices) | CHF 15,000 to 50,000 ex. VAT |
| Invitation competition (3 to 5 selected offices) | CHF 25,000 to 80,000 ex. VAT |
These indemnities cover a symbolic share of the actual work (which often represents 200 to 400 hours for a project competition). The economic model of the competition rests on awarding the mandate to the winner.
VAT on competition prizes
Competition prizes are subject to 8.1% VAT if the architect is VAT-registered. The client (particularly a public authority) pays the indemnity VAT-inclusive, and the architect declares it in the quarter of collection.
Warning: some public authorities draft their competition regulations with amounts VAT-inclusive or exclusive depending on the case. Always check in the competition program whether the announced indemnity is VAT-exclusive or VAT-inclusive to avoid a nasty surprise at collection.
Post-victory invoicing
The winner of a competition is awarded the mandate for subsequent phases (typically from phase 3). Invoicing then follows the normal SIA 102 scheme described in section 4. The competition indemnity is generally considered acquired and not deducted from the final mandate fees, unless expressly stated otherwise in the competition regulations.
A public mandate obtained through competition commits the winner to respecting the competition's conditions (team, approach, budget). Any deviation must be justified by a formal amendment.
8. Ancillary costs and disbursements
Color plans, models, prints
Disbursements are the expenses actually incurred by the architect on behalf of the client. They are distinct from fees as they are rebilled at cost (or with a reasonable margin generally capped at 10%). The main items:
| Item | Indicative amount | Rebilling method |
|---|---|---|
| A0 color plans, plotter print | CHF 15 to 40 / plan | At cost + small margin |
| Cardboard-wood study model | CHF 800 to 3,000 | Subcontractor, at cost |
| Presentation model (3D printing or model maker) | CHF 2,000 to 15,000 | Subcontractor, at cost |
| Photorealistic 3D rendering (subcontracted) | CHF 500 to 3,000 / view | Subcontractor, at cost |
| A3 / A4 color photocopies | CHF 0.50 to 2 / page | At cost |
| Bindings and application dossiers | Flat rate based on volume | At cost |
The contract must specify whether disbursements are rebilled at cost, with margin, or included in fees. The dominant practice: rebilling at cost with supporting documents, to avoid any suspicion of inflation.
Travel expenses
The architect's travel to the site, to the client's premises or to tender meetings is rebillable. Usual practice:
- Mileage: CHF 0.70 / km is the standard Swiss practice.
- Flat travel rate: CHF 50 to 150 depending on distance for a round trip.
- Travel time: billed at the hourly rate at 50% (custom) or 100% (if provided in the contract).
- SBB train fares: reimbursed at cost upon presentation of receipts.
Without explicit mention in the contract, a judge generally considers that local travel (less than 20 km) is included in the hourly rate or SIA lump sum, and that long trips are to be reimbursed at cost.
Rebilling external services
An architect may be required to coordinate external services (civil engineer, surveyor, acoustician, landscape designer) that they subcontract directly. Two models:
- Subcontracting by the architect: the architect pays the provider and rebills the client, possibly with a coordination margin (5 to 15%). VAT applies to the overall rebilled service.
- Direct contracts: the client contracts directly with each specialist. The architect only rebills their own coordination service.
Model 2 is fiscally healthier and limits the architect's exposure. It is preferable when the client is able to manage several contracts.
9. Recommended tools
Tobill for invoicing
An invoicing software suited to Swiss architectural practice must cover:
- Multi-phase management with tracking of interim statements per mandate.
- Automatic generation of QR-invoices compliant with Swiss Payment Standards, with structured reference by project and statement.
- Integration of hourly rates by collaborator category for time-based services.
- Rebilling of disbursements with attached supporting documents.
- Automatic VAT statement at 8.1% with quarterly declaration.
- Reminders with default interest at the legal rate of 5% for unpaid statements.
- Mobile application to record hours or generate a statement from the site.
Tobill covers these features with an interface designed for independent professionals and small Swiss offices. General accounting software (Bexio, Sage) is also suitable but requires heavier configuration for multi-phase billing.
CAD software: no direct invoicing
CAD software used in architecture (Archicad, Revit, AutoCAD, Rhino with BIM plugins) does not handle commercial invoicing. They manage drawing, BIM modeling, quantification and construction costs (to calculate the DCC), but fee statements must be issued from a dedicated tool such as Tobill, optionally connected to project data via CSV export.
The ideal flow: CAD for design and DCC extraction, SIA spreadsheet for calculating normative fees, invoicing tool for issuing statements with QR-invoice. This separation avoids overloading a tool with functions it is not designed to perform.
Project and time management software
For offices of more than 3 employees, a time tracking tool (Toggl, Harvest, or the time modules of Bexio / Abacus) becomes essential to justify time-based services. Integration with the invoicing tool allows timesheets to be transformed into statements in one click.
10. Architect FAQ
Can I bill outside the SIA scale if my client agrees?
Yes. SIA 102 is a normative reference, not a mandatory rule. A contract can deviate from the SIA formula provided the mode of remuneration is clearly defined and accepted by both parties. In the absence of contractual specification, a judge will refer to SIA practices to settle a dispute over the amount of fees.
A client refuses to sign an SIA contract. What to do?
Draft a simplified contract covering the essential points: scope of services, fee calculation method, phases and payment schedule, liability, termination. Explicitly include a clause referring to applicable SIA regulations for matters not addressed. It is an acceptable compromise for a small private client who refuses the complexity of a full SIA contract.
How do I bill a feasibility study that does not lead to a mandate?
The feasibility study is billed by time spent or on a lump-sum basis, as agreed. If the full mandate does not follow, the study remains acquired and billed. Provide in the contract a clause under which, if the full mandate is concluded later, the feasibility study may be partially credited against the fees of phases 1 and 2 (often 50%).
Is VAT due on the retainer at signing?
Yes, if you are under the effective regime: VAT is due at the time of collection of the retainer, to be declared in the corresponding quarter. This is the default collection-based chargeability rule. See our VAT declaration guide.
How to handle project modifications decided after validation?
Any modification requested by the client after validation of a phase gives rise to a contract amendment and an extraordinary service billed by time spent (unless the contract expressly provides for a lump-sum modification fee). SIA Regulation 102 frames this notion of extraordinary service: it is due as soon as the work exceeds the initial scope.
What to do if a client refuses to pay an interim statement?
Standard procedure: (1) amicable reminder with a copy of the contract and supporting documents for services performed; (2) formal notice with a 10-day deadline and default interest at the legal rate of 5% (art. 102 and 104 CO); (3) debt enforcement request to the Debt Enforcement Office. See our article on Swiss payment deadlines.
Does the competition indemnity actually cover the hours engaged?
No, rarely. Competition indemnities typically cover 20 to 40% of the actual time engaged. The economic model of the competition rests on awarding the mandate to the winner and the prestige that follows from a victory (new future mandates). Participate in a competition with a clear reading of this ratio, and balance your portfolio between competitions and direct mandates.
Should I mention my REG number on fee statements?
It is not a legally mandatory mention on a Swiss invoice (the mandatory mentions are name, address, UID, VAT number, dates, the ex. VAT/VAT/incl. VAT breakdown, IBAN). However, the REG number is an element of professional credibility strongly recommended, particularly for public mandates and large private clients. Add it to the header alongside your UID.
Summary: the invoicing circuit of a typical architect's mandate
For a full mandate for the construction of a residential building, DCC CHF 2,000,000, SIA fees CHF 210,000 ex. VAT, here is the complete circuit:
- Signing of the architect's contract based on SIA 102 with reference to applicable regulations.
- Retainer invoice upon signing: CHF 18,000 ex. VAT (approximately phases 1 and 2), VAT 8.1%, separate QR-invoice.
- Statement no. 1 at the end of phase 2: balance of preliminary studies, less the retainer.
- Statement no. 2 at the end of phase 3: CHF 44,100 ex. VAT for the project phase and permit application.
- Statement no. 3 at award: CHF 37,800 ex. VAT for the tendering phase.
- Monthly statements during phase 5: invoicing prorated to the progress of works, cumulative CHF 105,000 ex. VAT.
- Acceptance of the work with signed acceptance report and transfer of warranty.
- Final statement integrating phase 6 and any DCC adjustments.
- Archiving of files according to the 10-year accounting retention period (art. 958f CO, see the Swiss Confederation).
An architect who masters this circuit, equipped with an invoicing tool compliant with Swiss standards (QR-invoice, 8.1% VAT, multi-phase), turns each mandate into mastered and predictable revenue. Billing rigor is the first commercial skill of an independent architecture office: it distinguishes the professionals who thrive from the projects that exhaust them.