What is a reserve fund?

A reserve fund (sometimes called a sinking fund or capital fund) is money set aside every year to pay for large, predictable repairs — roof replacement, façade work, elevator overhaul — instead of hitting owners with a large one-off special assessment.

How much should a condo save each year?

A common rule of thumb is 10-25% of the annual operating budget, but the right number depends on the building's age, replacement value of common elements, and existing reserves. This calculator gives you an evidence-based starting point.

Is a reserve fund legally required?

In many jurisdictions (France, Portugal, Belgium, most of Canada) it is mandatory. Even where optional, banks and buyers increasingly expect one before financing a purchase in the building.

How is the contribution split between units?

Almost always by permillage (thousandths). A unit representing 250‰ of the building pays 25% of every reserve call.

Free tool

Condo reserve fund calculator

Estimate what your building should be saving every month for major repairs — based on the value of common elements, their remaining life, and reserves you already have.

Your building

Replacement value of common elements (€)Roof, façade, elevators, plumbing, common heating…Expected life of major components (years)30-40 years is typical for façade / elevatorsBuilding age (years)Reserves already saved (€)Number of units in the building

Monthly contribution per unit (avg)

€ 211

Split by permillage in practice — this is the building-wide average

Monthly for the whole building

€ 4,222

Annual total needed

€ 50,667

Normal €26,667 + catch-up €24,000

Reserve gap

€ 360,000

Straight-line target so far: €400,000

How is this calculated?

We use a straight-line depreciation model: over the expected life of major components, the building should accumulate reserves equal to their replacement value.

Target so far = replacement value × (age ÷ life). If you're behind, we spread the shortfall over the remaining years.

Annual contribution = normal depreciation + catch-up on the gap. Monthly is annual ÷ 12, per unit is monthly ÷ number of units.

This is an educational estimate. Real reserve studies model each component (roof, elevator, boiler…) separately and account for inflation and interest. Use this to spot-check your budget, not replace a professional reserve study.

Track reserves the easy way

CoCollab shows every owner exactly where the reserve fund stands — with monthly balances, transaction history, and a shared audit trail.

Try CoCollab free

All tools →Fee splitter →What is permillage? →