Each tenant only pays for their own tenancy
If a tenant moves out during the billing period, they only bear the service charges for the time of their tenancy. This means the allocable operating costs under section 2 BetrKV. There is no specific rule for splitting by time. Splitting to the day is common practice.
What counts is the term of the lease, not the key handover. A tenant who moves out before the lease ends bears the costs until the lease ends. Days between the end of one lease and the start of the next are vacancy. You bear that share as the landlord.
How the calculator splits to the day
Calendar days are counted, and both the move-in day and the last day of the lease count. 2024 has 366 days, 2025 has 365. CIRO calculates the amounts in whole cents: each share is rounded down, and the missing cent goes to the largest rounding remainder. That way outgoing tenant, incoming tenant and vacancy add up exactly to the unit's costs.
Share = costs of the unit × days of the tenancy ÷ days in the billing period
Worked example: move-out on 15 March
The billing period is 2025 with 365 days. The outgoing tenant's lease ends on 15 March 2025, the incoming tenant starts on 16 March 2025. The unit's share of property tax is €400.00.
- Outgoing tenant: 31 + 28 + 15 = 74 days, €400.00 × 74 ÷ 365 = €81.10
- Incoming tenant: 291 days, €400.00 × 291 ÷ 365 = €318.90
- Check: €81.10 + €318.90 = €400.00
The exact result for the outgoing tenant is €81.0959. Rounded down that is €81.09; the missing cent goes to them because their rounding remainder is larger.
Heating and hot water on a change of tenant
Heating and hot water fall under section 9b HeizkostenV. Every change of user requires an interim reading. The consumption part (50 to 70 %, as agreed for the building) is split by that reading. The remaining heating costs are split by degree days or by time, the remaining hot water costs by time.
If an interim reading is not possible or not precise enough, all costs are split by those measures: heating by degree days or time, hot water by time (section 9b (3)). Whether this also applies when a reading was possible but not taken is unresolved.
Heating costs belong to the period in which the heating was used, not to the payment date (BGH, VIII ZR 156/11).
Degree days: winter counts more than summer
Degree-day figures (Gradtagszahlen) spread the year by typical heating demand. January counts 170 ‰, June to August together only 40 ‰. Someone living there in winter therefore bears more basic heating costs than someone living there in summer. A part month counts pro rata by days.
Example with move-out on 15 March 2025 and €1,000.00 heating costs without an interim reading: the outgoing tenant gets 170 + 150 + 130 × 15 ÷ 31 = 382.90 ‰ and thus €382.90, the incoming tenant €617.10. Split purely by time it would be €202.74 and €797.26.
Degree-day figures per month (standard table)
| Month | Share of the year |
|---|---|
| January | 170 ‰ |
| February | 150 ‰ |
| March | 130 ‰ |
| April | 80 ‰ |
| May | 40 ‰ |
| June to August combined | 40 ‰ |
| September | 30 ‰ |
| October | 80 ‰ |
| November | 120 ‰ |
| December | 160 ‰ |
| Full year | 1,000 ‰ |
Which table counts as a recognised technical rule is not finally settled. CIRO uses the published standard table; the primary source (VDI 2067) was not reviewed.
Vacancy, overlap and special cases
- Gap between leases: you bear the days in between as the landlord.
- Overlap on the handover day: the day only counts once. CIRO assigns it to the outgoing tenant and points this out.
- Different billing period, e.g. 1 July to 30 June: twelve months still add up to 1,000 ‰.
- Cost of the interim reading: the change-of-user fee is not an allocable operating cost and therefore does not appear in the calculator.
- Different agreements under section 9b (4) HeizkostenV are not covered by the calculator.