German Heating Law for Landlords: Deadlines 2026

Few pieces of legislation have unsettled German property owners as much as the Gebäudeenergiegesetz (GEG) – the Buildings Energy Act, which almost everyone calls the „Heizungsgesetz“ (heating law). The most widespread belief – that every heating system older than 30 years has to go, and that only heat pumps may be installed from now on – is not correct in that form. This article works through the statute from a landlord's point of view: what is genuinely mandatory, by when, and how much of it you may pass on to the rent.

The 65 percent rule applies on installation – not to your existing system

The core sentence sits in § 71 para. 1 GEG: a heating system may only be installed or set up for the purpose of commissioning „if it generates at least 65 percent of the heat provided by the system from renewable energies or unavoidable waste heat“.

The operative word is installed. The duty attaches to the installation, not to the age of the system you already have. For your existing portfolio that means:

How you meet the 65 percent is up to you: § 71 para. 2 GEG expressly leaves the choice of system free. § 71 para. 3 GEG lists seven types for which the requirement counts as met without a calculation – among them a connection to a heat network, an electrically driven heat pump, solar thermal, biomass, and heat-pump or solar-thermal hybrid systems. Anyone choosing a different route needs a certificate under DIN V 18599 issued by an authorised person, to be kept for at least ten years.

How long you may still install a fossil-fuel system

In existing buildings a transitional rule applies that is tied to municipal heat planning (§ 71 para. 8 GEG). What matters is the municipality's population as at 1 January 2024:

The dates in the right-hand column follow from § 4 para. 2 of the Wärmeplanungsgesetz (Heat Planning Act): by then the federal states must ensure that heat plans have been drawn up.

Conversely: if no heat plan exists once the relevant deadline has passed, the municipality is treated as though one did – the duty then applies anyway.

Installing gas now creates a follow-on obligation

A fossil-fuel system installed under the transitional rule is not a worry-free solution. Under § 71 para. 9 GEG its operator must ensure that from 1 January 2029 at least 15 percent, from 1 January 2035 at least 30 percent and from 1 January 2040 at least 60 percent of the heat provided comes from biomass or green or blue hydrogen. How those quotas will be sourced, and what the fuel will then cost, is hard to price today – a risk that belongs in the investment case.

Consistently with that, § 71 para. 11 GEG requires advice before a solid, liquid or gaseous fuel system is installed. It must expressly point out the possible effects of heat planning and the possibility that the system turns out to be uneconomic, in particular because of rising carbon pricing.

The operating ban on old boilers – and why it bites less often than people think

Independently of the 65 percent rule, § 72 GEG contains a genuine operating ban:

The trap when buying a one- or two-family house

§ 73 GEG is particularly relevant for buyers. For a residential building with no more than two flats, one of which the owner occupied themselves on 1 February 2002, the duties under § 72 paras. 1 and 2 GEG only have to be met „in the event of a change of ownership after 1 February 2002, by the new owner“. Under § 73 para. 2 GEG the deadline is two years from the first transfer of ownership after that date.

In practice: an old system that ran unchallenged at the seller's for decades can become your obligation on completion – on a hard two-year clock. That belongs in the price negotiation and in the cash-flow calculation, not in the „sometime later“ pile.

If the heating fails: a five-year transitional period

If the system fails after the 65 percent duty has taken effect in your municipality, § 71i GEG allows a general transitional period: for a maximum of five years a system may be installed and operated on a transitional basis that does not meet the requirements of § 71 para. 1 GEG. The period starts on the day the replacement work is first carried out – a second replacement within that window does not extend it. The general period expressly does not apply to flat-level heating systems, single-room fireplaces or hall heating; separate rules govern those.

What you may pass on to the rent

Replacing the heating is a modernisation measure for which the German Civil Code provides its own route. Under § 559e para. 1 BGB the landlord may increase the annual rent by 10 percent of the costs incurred for the flat less any third-party funding drawn down – provided the measure meets the conditions for a subsidy in principle and subsidies were actually claimed. Under § 559e para. 3 BGB this is capped at 0.50 euros per square metre of living space within six years. We have worked through the mechanics of the pass-through – maintenance share, deductions, capping limits – in a separate article on the modernisation surcharge.

And the tax side?

Replacing the heating in a let property is normally maintenance expenditure (Erhaltungsaufwand) and therefore immediately deductible. Take care if the replacement falls within the first three years after purchase: it can then run into the 15% threshold for acquisition-related production costs and has to be depreciated over the useful life instead of taking effect at once. Subsidies claimed also reduce the depreciation base.

Frequently asked questions

Do I have to replace my 25-year-old gas heating now?

No – not on account of the 65 percent rule, which applies on installation. An operating ban under § 72 GEG only bites after 30 years, and even then not for low-temperature and condensing boilers.

May I still replace a broken gas boiler with another gas boiler?

Within the transitional windows of § 71 para. 8 GEG yes, provided no heat network decision has been announced for your area. After that, the five-year period under § 71i GEG applies. In both cases you take on the quota obligation of § 71 para. 9 GEG.

Does the GEG also apply to condominiums with flat-level heating?

Yes, via a procedure of its own: § 71n GEG obliges the owners' association among other things to gather information on the existing flat-level systems, to adopt an implementation concept and to report on progress at least once a year. The cost of converting to a central system is borne in proportion to the co-ownership shares.

When are fossil-fuel systems finally banned?

§ 72 para. 4 GEG sets a hard limit: boilers may be operated on fossil fuels at the latest until the end of 31 December 2044.

This article provides general orientation and does not replace individual tax or legal advice within the meaning of § 3 StBerG. What counts is the wording of the statute as currently in force, your local municipal heat planning, and advice from an authorised professional.