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Calculator technical methodology

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This document explains the origin and status of every input used by the pay-discrimination evaluator and the fee band estimator, so that anyone using them can tell apart a regulatory figure, an unofficial industry benchmark, and a working assumption of the model — editable and open to debate. Both tools share the same calculation engine (hour estimation, cost floor, MEF floor).

Both calculators include a year selector (2024–2027), because the collectively-bargained salary, the SMI (national minimum wage) and the Deltek utilization rate do vary from one year to the next (unlike the Italian model or SEGIPSA, which do not depend on the year). See section 6 for the detail of what changes by year and what stays constant for lack of published data.

It is not a tariff or a fee scale: it is a cost-justification methodology, built from explicit layers.

1. Table of sources

Input Value Status
Reference salary (collective agreement) €28,664/year (2024–2027) Level 1, 2024 salary tables of the 20th Collective Agreement for engineering and technical consultancy firms — collectively-bargained (BOE-A-2024-5873, 12/3/2024). No agreed table for 2025–2027; the 2024 figure is kept — see section 6
Employer social security contribution 33.01% of the base salary Regulatory Social Security calculation on the collectively-bargained salary or the SMI — regulatory (percentage held constant between 2024 and 2027 as a simplification; does not incorporate the annual increase of the Intergenerational Equity Mechanism)
Operating costs (Madrid) €17,569/year (rent €10,500, professional liability insurance €1,000, remainder) Average market values in Madrid — working assumption, conservative and editable; with no single reference year, applied equally across the four years in the selector
Annual hours 1,792 h Maximum working hours under the engineering and technical consultancy collective agreement — collectively-bargained
Utilization rate 59.3% (2024–2027) “Architecture or A/E” segment, fiscal year 2025 — 47th Annual Deltek Clarity A&E Industry Study (Deltek / CMG Consulting), “Statistics at a Glance” table, p. 122 (the narrative median for the whole A&E sector, not just architecture, is 58.9%, p. 99) — industry benchmark, U.S., not an official Spanish figure (full report). The only architecture-specific figure published; applied equally across the four years in the selector — see section 6
Reference gross remuneration (cost floor) €38,345/year Average between ACE 2020 public-sector employment (€44,512) and private-practice management (€32,178) — working assumption, with a starting figure from the Architects’ Council of Europe
Employer cost-multiplier coefficient 1.356 Ratio of gross cost / wages and salaries, Services sector — INE, Annual Labour Cost Survey (EACL), 2025, Table 1 (€37,717.75 / €27,817.39) — industry benchmark (Spain); the INE does not break this down by a finer branch of activity, so the Services sector as a whole is taken as a proxy for architecture
Overheads / industrial profit (cost floor) 13% / 6% By analogy with art. 131 RGLCAP (public works) — regulatory by analogy, not a figure specific to the architecture sector
SMI (national minimum wage) €15,876 (2024) / €16,576 (2025) / €17,094 (2026–2027) Regulatory — BOE-A-2024-2251, BOE-A-2025-2576, BOE-A-2026-3815. No Royal Decree published yet for 2027; the 2026 figure is kept
Amount→hours conversion rate 50 × 1.21 (Italian CPI 2016→2024) = €60.5/h Lower end of the band under art. 6.2 of DM 17/6/2016, updated — updated regulatory figure
Parameters V, G, Q, P (Italian model) Tables Z-1 and Z-2 DM 17/6/2016 — regulatory (Italy); the G and ΣQ used by this tool are an indicative aggregated categorisation, not the decree’s line-by-line breakdown — see Legal Framework
DM 2016 public-works maximum rebate 65% fixed / 35% open to rebate; 20% for direct award (< €140,000) As of 1/1/2025, the Italian Codice dei Contratti Pubblici (D.Lgs. 209/2024, amending D.Lgs. 36/2023) limits the admissible rebate on the DM 17/6/2016 parametric tariff: in a tender, 65% of the tariff is fixed (not reducible) and only the remaining 35% can be rebated, which sets the maximum discount range; for direct award (commissions under €140,000), the maximum admissible rebate is 20% — regulatory (Italy), cited as a comparative reference, not applicable in Spain
% of PEM (SEGIPSA) 6.65%–3.08% depending on bracket and item Resolution of 11/5/2015 (BOE 27/5/2015) — regulatory, verified against the official text

2. Derivation of the cost floor (€58.23/h)

  1. Reference gross remuneration: €38,345/year.
  2. × employer cost-multiplier coefficient (1.356 — INE, EACL 2025, Services sector): gross cost to the employer.
  3. ÷ (1,792 annual hours × 59.3% utilization rate — Deltek Clarity A&E): cost per effectively billable hour.
  4. × (1 + 13% overheads + 6% industrial profit): adds overheads and industrial profit by analogy with art. 131 RGLCAP.
  5. Result: €58.23/h.

This floor answers the question “how much does it cost a practice to produce one hour of work, including its margin?” — it is a cost floor, not an anti-discrimination floor. A fee below this floor is not necessarily discriminatory, but it does indicate a price lower than adequate.

3. Derivation of the MEF floor (by year — see table in section 6)

  1. Reference salary for the selected year (collectively-bargained; or the SMI, depending on the chosen base) + employer social security contribution (33.01% of the base salary) + Madrid operating costs (€17,569).
  2. ÷ 1,792 annual hours.
  3. Result: the actual anti-discrimination floor (collective-agreement base) — the direct comparison with what it would cost to hire an employed professional with the same qualification — and, on the SMI base, the absolute threshold. The values for 2024–2027 are in section 6.

This floor is the foundation of MEF: a self-employed worker should not earn, for equivalent work, less net remuneration than a salaried worker would receive for the same work.

4. Automatic estimation of commission hours (HME)

Explained in detail on the Evaluator page: in summary, the DM 17/6/2016 formula itself — CP = V·G·ΣQ·P, with the flat-rate expenses under art. 5 — is applied to the PEM entered, where:

  • V = the PEM (value of the works) entered by the user.
  • G = grado di complessità (degree of complexity), read from Table Z-1 according to the building type and degree of complexity chosen.
  • ΣQ = aggregated incidence of the commission’s phases (Table Z-2), according to the scope selected (drafting, supervision, or both, with or without safety coordination).
  • P = 0.03 + 10/V^0.4, the decree’s own decreasing parametric factor as a function of V.

The result (CP, in euros) is converted to hours by dividing by the conversion rate of €60.5/h.

5. Explicit limitations

  • Data marked as a working assumption are editable and open to debate: they represent a reasonable, documented estimate, not a matter of regulation. Anyone who disagrees with one can recalculate the floor with their own values.
  • The utilization-rate benchmark (59.3%, Architecture/A-E segment, fiscal year 2025) comes from a U.S. industry source (Deltek Clarity A&E), not from official Spanish data, for lack of an equivalent study published in Spain. It is an annual sector figure that varies from year to year; the most recent edition of the study should be reviewed periodically.
  • The employer cost-multiplier coefficient (1.356) comes from the ratio of gross cost / wages and salaries for the Services sector in the INE’s EACL 2025, not from a figure specific to architectural practices or professional firms; the most recent edition of the EACL should be reviewed periodically.
  • Operating costs (€17,569/year) are calculated for Madrid; in other cities or regions the cost floor will vary.
  • The building-type/complexity categorisation (parameter G) and the ΣQ for the commission’s scope are indicative simplifications of Tables Z-1 and Z-2 of DM 17/6/2016, not the official full breakdown by subcategory.
  • The SMI and the conversion rates should be updated periodically in line with CPI; the figures here reflect the latest verified values.

6. Data and results by year (2024–2027)

Both calculators let you choose a reference year because the collectively-bargained salary, the SMI and the Deltek utilization rate are published (or not) year by year — unlike the Italian model or SEGIPSA, which do not depend on the chosen year. The band estimator defaults to the current year; the pay-discrimination evaluator requires an explicit choice of year, with no default, so as not to presuppose a given year in a comparative calculation.

Year Collective-agreement salary SMI MEF floor (collective agreement) MEF floor (SMI) Cost floor Notes
2024 €28,664 €15,876 €31.08/h €21.59/h €58.23/h All figures are official or the reference benchmark (FY2025 Deltek, EACL 2025) verified for this year
2025 €28,664 (no agreed table; 2024 kept) €16,576 €31.08/h €22.11/h €58.23/h Official 2025 SMI; utilization rate and cost-multiplier coefficient with the latest published editions (Deltek FY2025, EACL 2025)
2026 €28,664 (no agreed table; 2024 kept) €17,094 €31.08/h €22.49/h €58.23/h Official 2026 SMI; utilization rate and cost-multiplier coefficient with no more recent edition, Deltek FY2025 / EACL 2025 kept
2027 €28,664 (no agreed table; 2024 kept) €17,094 (no RD published; 2026 kept) €31.08/h €22.49/h €58.23/h A year with no figure of its own published yet; all figures are the latest available

The cost floor does not change between 2024 and 2027 because its only three year-sensitive inputs — the reference gross remuneration (ACE 2020, a working assumption with no annual series), the Deltek utilization rate (FY2025, the only architecture-specific figure available) and the employer cost-multiplier coefficient (EACL 2025, Services sector) — are held constant for lack of an applied time series. The year selector is already set up to reflect the change automatically once a new edition of the Deltek study, the EACL, or an updated working assumption for gross remuneration becomes available.

The employer social security contribution is calculated as a fixed percentage (33.01%) of the base salary for each year, without modelling the annual increase of the Intergenerational Equity Mechanism (MEI), which raises the contribution rate slightly each year; this is a deliberate simplification, consistent with the rest of the model’s “working assumptions.”

More information

Pay-discrimination evaluator → Fee band estimator → See the full Legal Framework →

Last updated: September 2026