Rental apartment building valuation: which rent assumptions need clarification?

Which documents belong to a tenancy?

Start with the signed agreement, all amendments, handover documents and adjustment letters. Add relevant agreements on payment deferrals, investments, subletting or changes of use, and court or administrative decisions. A contract summary from the property manager makes the work easier but does not replace a missing document. Deviations followed in practice also belong in the review file.

Link the documents using the unit identifier in the rent roll. Record the contracting parties and any changes to them, the precisely defined rental premises, and ancillary rooms and areas included in the letting. A commercial lease may cover several rooms listed separately in the area schedule. Without this reconciliation, floor-area rates may be incorrect or ancillary charges counted twice.

Why the construction year cannot replace a full legal review

§ 1 MRG distinguishes between scopes of application and exemptions. Classification may depend, among other things, on construction and approval history, public funding, condominium ownership, how individual units were created and contract dates. An attic rental unit created later may therefore be subject to different requirements from an existing apartment in the same building. Subsidy law and particular contractual circumstances must also be examined.

Keep one row per unit showing its provisional classification and the evidence actually available to support it. Label assumptions explicitly. In Vienna, owners, property managers and duly authorised persons can inspect approved building plans in the MA 37 archive. The plans help reconstruct the history and use; the legal conclusion can only be reached by considering all the evidence together.

Foundations: RIS – Bundeskanzleramt [1] · Stadt Wien – MA 37 [4]

Check rent setting and indexation separately

The question of the permissible initial rent comes before updating it. Where § 16 MRG applies, the requirements of the relevant rent-setting method and the specific contract date are decisive. The label in the agreement or a comparison of listings does not establish a legally defensible amount. Existing agreements also require consideration of historical rules and subsequent agreements.

For indexation, document the wording of the clause, reference index, initial value, threshold, adjustment letters and implementation to date. Have its validity and the statutory limits applicable on the valuation date checked. A general inflation assumption must not replace the unresolved legal question. Record a potential change as an amount with its earliest effective date before it enters the income plan.

Foundations: RIS – Bundeskanzleramt [2]

When can a later reletting be assumed?

Record the signing date, commencement date, end date agreed in writing and every extension separately. Among other matters, § 29 MRG governs the requirements for fixed terms and the consequences of continued use. The version in force since 2026 also distinguishes residential fixed terms according to whether the landlord acts as a business. Contract and extension dates and transitional provisions must therefore be checked; an older table rule using the same minimum term in every case is inadequate.

Even a valid fixed term does not make the later cash flow certain. A planned extension, actual return of the unit, reinstatement work and marketing time affect the start of a new agreement. For open-ended agreements, a desired change of tenant must not be modelled using an arbitrary date. Necessary legal steps and possible outcomes remain explicitly unresolved while evidence is missing.

Foundations: RIS – Bundeskanzleramt [3] · RIS – Bundeskanzleramt [1]

Turn the contract review into a useful list of assumptions

Transfer only the result of each review into the income assumptions: documented existing arrangements, a professionally confirmed change or a conditional scenario. State which unit is affected, when the amount changes and which evidence supports that change. An unresolved legal dispute receives its own description of possible financial and timing consequences.

Prioritise review tasks according to their influence on the decision. An unclear contract end date for a large commercial unit may matter more than a small rounding error in an ancillary area. When the work is complete, the valuation professional should be able to identify which income is reliably documented and where an additional legal review could materially change the result.