User Interface

The user interface should be clear, concise and crisp, as lot of typical financial data is involved in the system, the user should not get baffled in entering the input or reading the output. Once user interface is made it should be given to end user for trial basis so that he gets equipped to the software.

Business Logic

No matter how easy it is to use software, the software will be of no use if it is not performing the basic required task correctly. So while designing and even after designing lot of back testing should be done with the available data so as to make sure that calculator is giving correct results.

Robustness

Since financial calculations involve a lot of numerical data, the software should also be tested for robustness, it should be able to handle large amount of data efficiently. For this stress testing of the software should be done by exposing it to extreme values.

Scalability

In the fast changing financial environment we see many changes being done in the policies, introduction of new financial instruments and use of newer and more efficient algorithms. In this view the software should be scalable to future needs.

Modularity

The software should also be modular for easy maintenance. This also helps in making any future changes to the software. Loose coupling of various components is always advisable.

Above points may seem to be a bit technical but while designing or buying technology product or service knowledge this aspect is a must. Thus if we keep above given points in mind and then go for buying or designing a financial software, we will be able to make a better and informed decision.