## Accounting Rate of Return (ARR)
ARR measures the average annual net income (incremental income) as a percentage of investment. Unlike payback, it uses accounting profit, not cash flow.
```
ARR = Average annual net income / Investment x 100
```
- Numerator: average annual net income (profit after depreciation, and after tax if applicable) over the project's life.
- Denominator: either the initial investment (incl. installation) or the average investment.
### Average Investment
```
Average Investment = (Initial Investment + Salvage Value) / 2
= 1/2 (Initial Investment - Salvage) + Salvage
```
If additional working capital is required during the project:
```
Avg Investment = 1/2 (Initial Investment - Salvage) + Salvage + Additional Working Capital
```
### Three Versions of ARR
1. Annual basis: compute ARR each year on opening investment, then average the percentages.
2. Total Investment basis: Average annual profit / Initial investment.
3. Average Investment basis: Average annual profit / Average investment.