Operating Cost Billing Software: Features, Deadlines and the Right Fit for Your Portfolio

Good operating cost billing software does far more than divide costs at year-end. It imports consumption data automatically, allocates costs correctly and produces heating and operating cost statements that hold up against the requirements of the German Heating Costs Ordinance and the CO₂ Cost Allocation Act. For housing companies and property managers, and for metering service providers too, the degree of automation decides how much manual work ultimately lands on your desk.

Industry figures put operating costs at up to 40 percent of a property's total costs, which is exactly why billing errors turn expensive fast, both financially and legally. At the same time, the CO₂ Cost Allocation Act and the interim consumption information requirement have raised the bar on data quality and deadlines considerably. Choosing the right software here mainly buys you time and legal certainty across the whole portfolio, whatever the number of units you manage.

Four factors decide in practice whether billing software actually takes work off your plate:

What Features Should Operating Cost Billing Software Include?

Complete operating cost billing software covers the whole path from capturing costs to producing the finished, legally compliant statement. Seven functional building blocks decide how much manual work actually disappears.

Middleware, briefly explained: Middleware connects the billing system and the user portal to external interfaces, so data flows between systems without manual handover, from meter capture right through to the finished statement.

The effect shows up most clearly in consumption data import. Where estimates or manual transfers used to be the norm, measured values are now available straight from the metering service system. The same shift happens in CO₂ monitoring, where measured data is replacing estimated figures, and billing follows the same principle.

What Role Do the CO₂ Cost Allocation Act and Interim Consumption Information Play in Choosing Software?

Three legal deadlines currently determine which billing software even qualifies as an option: the cut-off period under Section 556 of the German Civil Code (BGB), the CO₂ Cost Allocation Act and interim consumption information requirements.

Under Section 556(3) BGB, the operating cost statement must reach the tenant no later than twelve months after the end of the billing period, otherwise the landlord loses the right to claim any additional costs. Software that pulls invoices together automatically and tracks deadlines lowers exactly this risk, measurably.

Since 1 January 2023, the CO₂ Cost Allocation Act has required landlords to cover a share of the CO₂ costs on heating oil, gas and district heating, tiered under a ten-step model based on emissions per square metre per year. Non-residential buildings still work on a fixed 50/50 split.

A first assessment of the CO₂ Cost Allocation Act: The German Federal Ministry for Economic Affairs published its first evaluation report in April 2026, finding that the cost share landlords actually carry is considerably smaller than the tenants' share in practice. Across all tenancies, billing has yet to reach a genuine fifty-fifty split.

Landlords with remote-readable meters have had to give tenants a monthly interim consumption information statement since 2022 already. From 2027, this obligation applies to all residential buildings across the board. If the statement is missing, tenants can cut their heating cost share by 3 percent on their own under Section 6a of the Heating Costs Ordinance, an amount that adds up quickly across a large portfolio.

Where property management stands today: A VDIV survey of more than 300 property management companies found that, 23 months before the deadline, 58 percent of owners' associations and 61 percent of rental properties already have remote-readable meters installed. Yet only 32 and 39 percent of owners and tenants respectively actually receive a regular interim consumption statement, and a quarter of management companies do not deliver one at all so far.

For these deadlines to stay technically achievable, the software needs one thing above all: reliable, standardized data exchange with metering and ERP systems.

Automation, Data Quality and Scalability: What to Watch for Across Your Portfolio?

Three technical criteria decide whether billing software genuinely saves work day to day: how much it handles automatically, how clean the consumption data arrives, and how well it scales alongside a growing portfolio.

On automation, it pays to check every single step of the chain, from meter reading through invoice checking to cost allocation. The more of that runs without manual intervention, the less staff time is needed as unit counts grow. On data quality, the Federal Association for Energy and Water Data Management has published a new generation of standardized API web services, covering things like user roles and billing results, that make data exchange between housing companies' ERP systems and metering service providers directly controllable.

The GdW calls in its digitalization position paper for consumption data from metering devices to be used holistically for billing, tenant information and energy savings, since that contributes to CO₂ reduction in building operations in the short term. We take a closer look at how granular consumption data can serve reporting beyond pure billing in our article on ESG data in real estate.

Vendors now position their software openly by portfolio size. DOMUS 1000 targets smaller management companies with up to around 500 units, while DOMUS ERP is built for medium to large housing companies with as many as several tens of thousands of units. Scalability is a selection criterion in its own right, shaping the management company's own operating costs well beyond the technology itself.

Plan for migration risk: Aareon Wodis Sigma is an established industry standard with a historical customer base of more than 1,000, but support runs only until the end of 2028, after which it will be discontinued in favor of the cloud-based successor Wodis Yuneo. Anyone still billing on Wodis Sigma today is best off factoring the switching effort into the current software selection.

How Much Work Does Automated Billing Save Compared with Manual Workflows?

Automated billing cuts effort mainly on meter readings and invoice checking, and also on communication with tenants and owners. Done manually, that means every month typing meter readings in from lists and checking invoices one by one against contracts, plus answering queries individually by phone or email.

A VDIV survey found that 22.2 percent of property management companies already use AI tools daily, with a further 45.1 percent planning to adopt them. AI is currently most widespread in customer communication, at 55.4 percent. Vendors report time savings from AI-supported invoice capture of roughly 40 to 80 percent depending on the provider, a rough figure from manufacturer claims rather than an independently measured market average.

For a portfolio with several thousand units, that translates into a case handler reviewing only the anomalies the system flags, while the software codes the rest automatically. The property manager portal also takes over part of the communication, since owners and tenants can check statements and status themselves without writing an email.

Dedicated Billing Software or Property Management Software with a Billing Module: What Fits Your Portfolio?

The choice mainly depends on whether billing is your core business or one building block alongside letting and owner communication. Metering service providers and dedicated billing service providers need software built for hundreds of thousands of units a year, one that handles billing as a high-volume business.

Management companies with a few hundred to a few thousand units, on the other hand, often manage fine with property management software that ships billing as an integrated module alongside accounting and other administrative tasks. The advantage is having one system for every process; the drawback shows up once the billing module falls short of dedicated software on automation depth or interface quality. Before signing a multi-year contract, it's worth running a direct feature comparison between the billing module and a standalone solution.

For housing companies with a growing portfolio, it also matters how a vendor handles end-of-support situations. The switch from Wodis Sigma to Wodis Yuneo is a good example of how even established ERP standards can trigger migration projects that need planning well ahead of time.

Where Does the KUGU Messdienstplattform Fit into This Choice?

The KUGU Messdienstplattform is built for exactly this scenario: specialized software for heating and operating cost statements, kept separate from the KUGU Energieplattform, which handles heating optimization during day-to-day operation. Anyone looking to control and optimize plant equipment will find that on the Energieplattform. Billing and submetering at KUGU, meanwhile, run through the Messdienstplattform.

Its core product, KUGU AbSys (short for Abrechnungssystem, billing system), is used every year for more than 500,000 units and is regarded as an established billing standard in the housing industry. On this basis, KUGU has digitized more than 300,000 residential units in total and connected over 3,000 heating systems.

At KUGU Days 2026, KUGU introduced new middleware that links AbSys more closely with Portal 2.0, the data pipeline and external interfaces, automating data flows from capture through billing to delivery. Building on that, AI agents are set to be integrated into billing processes over the coming months. Our article on AI-based energy optimization shows how AI is already steering heating operations on the energy side.

Anyone still billing their portfolio through Excel lists or property management software without a robust billing module will find a concrete starting point for the next tender in Portal 2.0 and the AbSys interfaces.

Regulation and Automation: Why the Window Is Closing Now

The real news in this comparison isn't a single feature; it's the timing. From 2027, interim consumption information becomes mandatory for all residential buildings, while CO₂ cost allocation and standardized data exchange are already in force today. Anyone who leaves the software decision until shortly before the deadline ends up migrating under time pressure and with a smaller field of vendors to choose from.

Look at automation, interfaces and scalability early, though, and there's more room to handle the technical rollout and compare several vendors without rushing. That applies just as much to housing companies with growing portfolios as it does to metering service providers, whose own customers increasingly ask about bved compliance and AI-supported automation.

For housing companies and property managers with a growing portfolio, it's worth running a structured comparison against the criteria in this article before the next billing season starts. Metering service providers should also check whether their current system already supports bved data exchange standards or still needs to be retrofitted.

Frequently Asked Questions About Operating Cost Billing Software

How Long Can an Operating Cost Statement Take After the Billing Period Ends?

Twelve months from the end of the billing period; after that, landlords lose the right to claim additional costs under Section 556(3) BGB. This deadline applies whether the statement is prepared manually or with software. Credits owed to tenants are not affected by this cut-off period.

What Happens If No Interim Consumption Information Is Provided?

Tenants can cut their heating cost share by 3 percent on their own under Section 6a of the Heating Costs Ordinance if the statement is missing. That applies for every month the information wasn't provided. Across larger portfolios with several properties, this amount adds up quickly.

Do Landlords Have to Cover Half of the CO₂ Costs?

No, statements in practice don't reach a genuine fifty-fifty split. The German Federal Ministry for Economic Affairs' first evaluation report from 2026 shows the landlord's share coming out considerably smaller, on average, than the tenant's share. The CO₂ Cost Allocation Act's ten-tier model is based on CO₂ emissions per square metre per year.

Which Interface Do Housing Companies Need for Data Exchange with Metering Service Providers?

The standard from the Federal Association for Energy and Water Data Management, with web services such as Billing Input and Billing Result, governs data exchange between ERP systems and metering service providers today. Software without support for this standard typically creates extra manual steps in every billing round. For tenders, it's worth asking specifically which interface version a vendor supports.

From When Does Interim Consumption Information Apply to All Residential Buildings?

From 2027, the interim consumption information obligation applies to all residential buildings across the board, regardless of the metering technology in place. The deadline for full rollout of remote-readable equipment runs out on 31 December 2026. Landlords with remote-readable meters have already had to supply the monthly information since 2022.