Summary
On this page you'll find information on how to transition from FinFlow to InterestThing. Feel free to contact us if you didn't find what you were looking for.
Developing InterestThing offered the opportunity to restructure the way the various compute options were presented.
Settings now let you choose between simple and compound interest and combine the interest type with the two main methods of calculating time between dates: standard day count conventions and periods and days (what we called the actuarial method in FinFlow).
Day count conventions were revised and are now structured and named as defined in the ISO 20022 standard.
Reference dates were added to the periods and days method to solve the problem of implicit capitalization.
Frequently asked questions
Can InterestThing perform the same calculations as FinFlow?
InterestThing can do all the calculations that you did with FinFlow and more.
As you can now combine interest types with how time between dates is calculated, it provides ways to calculate interest that were not available in FinFlow.
The addition of reference dates to the Periods and Days method (the old Actuarial method) adds even more possibilities.
Can InterestThing open my old FinFlow documents?
InterestThing can read and import legacy FinFlow documents!
To open a FinFlow document select Open... from the File menu, double-click it in the Finder or right-click the document in the Finder and select Open With > InterestThing.
This will open a new InterestThing document with the name of the selected file and add "imported" to the filename. Your FinFlow document remains as it is.
When you save the imported document, it will be saved as an InterestThing document.
Why do my old FinFlow documents have generic icons?
You may have noticed that legacy FinFlow documents lost their icon on newer macOS versions. This is because macOS assigns generic icons to files it can't link to an application. Adding the extension "finflow" fixes this.
We've created an utility that scans a folder for legacy FinFlow documents, and adds the "finflow" extension to the legacy files it finds.
To rename your old FinFlow files, select Add FinFlow Extensions... in the Window menu or press Command-Shift-E. Then select the folder with your old files to batch rename them.
What is different in InterestThing compared to FinFlow?
1. New Compute options
Compute options have been reorganised so that there is now a clear distinction between interest types and the way time intervals are calculated.
In FinFlow the compounding frequency or periods popup, along with the US Rule checkbox were located in the Cashflow window: these are now located in the Compute options sheet. Extra options appear depending on the selected methods.
FinFlow's Compound interest method calculated compound interest using year fractions.
When the compounding frequency was set to "none" it calculated simple interest using year fractions.
To match FinFlows Compound interest method:
First, set Date intervals to year fraction, then:
- for normal compounding frequencies, set Interest type to compounded.
- for the "none" frequency, set Interest type to simple.
FinFlow's Simple interest method calculated simple interest using periods and days.
To match FinFlows Simple interest method:
Set Interest type to simple and Date intervals to periods and days.
FinFlow's Acuarial interest method calculated compound interest over periods and days.
To match FinFlows Actuarial interest method:
Set Interest type to compounded and Date intervals to periods and days.
Simple capitalized interest lets you capitalize on the item date as it was done in FinFlow. Please note that compound interest now always uses reference dates.
2. Day count conventions are now standardized
FinFlow used a wide variety of day count conventions, which at the time FinFlow was developed were not uniformly defined, hence the many different names for the same methods.
InterestThing now uses the methods of interest computation (MICO) defined in the ISO 20022 standard.
Corresponding methods in FinFlow were renamed to the new standard methods, missing methods such as 30E3/360, 30/Actual and Actual/Actual (ICMA) were added.
Older methods provided in FinFlow which are not described in the ISO 20022 definitions are included in the "Other" category so that they can still be used in InterestThing.
InterestThing lets you import legacy FinFlow documents from all previous versions, and automatically converts the old settings (both compute methods and day count conventions) to the new ones.
IMPORTANT
The old FinFlow 30E/360 day count convention has been renamed to the new 30/360 ICMA day count convention
The old FinFlow 30/360 BMA day count convention, has been renamed to the new 30E/360 Eurobond basis day count convention.
The old FinFlow 30/360 SIA and 30/360 US day count conventions used the same algorithm, therefor FinFlow documents using the old 30/360 US day count convention will be imported as using the 30/360 SIA day count convention.
An overview of the available conventions can be found here, along with the corresponding names used in FinFlow.
3. The Periods and Days method can use reference dates
The addition of reference dates when using periods and days to calculate capitalized simple interest and compound interest effectively solves the problem of the implicit compounding that occurs when interest is added to the balance at irregular intervals.
Where applicable it is now possible to specify whether capitalization or compounding occurs from date to date (as used in FinFlow) or on relative reference dates depending on the selected periods and either the date of the first event or a custom reference date.
4. Changed behaviour of Balance date and Rate change events
Under certain circumstances, balance dates and rate changes could influence the balance in FinFlow, due to implicit capitalisation or compounding.
When a rate change occurs inside a period in the Periods and Days method, interest will be calculated up to that date at the old rate and is internally kept pending until the next compounding or capitalisation date, at that date it is added along with further accrued interest at the new rate since the rate change date.
You can now add as many Balance date events as you like. The application will calculate the balance up to that date, but it will only change the actual balance when a payment event (i.e. any event but a Balance Date or Rate Change event) is encountered.
If you want to mimic the old behaviour, replace them with or add zero amount inflow events.
5. New Details tab
The Cash Flow Window now has a Details pane which let you examine the way time between dates is calculated for the current cash flow.
When applicable, the Schedule pane has extra columns for a detailed breakdown of accrued interest in capitalized/compounded interest, pending interest and interest due.
6. New utility windows
To test our time interval calculations, we added custom windows that calculate time between dates as year fractions or as periods and days using sample data sets found in the documentation of various day count conventions.
As the data for these sets are set up specifically to show the differences between day count conventions, it is a good way to figure out how a particular day count convention actually calculates and what it does differently compared to other conventions.
If you want to use your own data sets, you can import them into the Custom set.
The Day Count Conventions Window lets you compare the different day count conventions. The Help button displays the definition for the selected convention.
The Periods and Days Window shows how different interest period and year lengths settings produce a number of full periods and odd days and the corresponding periods and days fractions.
The Rate Conversion Window offers a number of conversions between nominal, effective, equivalent and periodic rates.
To compare different settings side by side, just open multiple utility windows.
7. Importing and exporting data
InterestThing lets you import payment and rate data using tab separated text files.
InterestThing lets you export document data as text files with tab separated values and in the Portable Document Format (PDF).
An exported PDF file can then be opened in Preview, from which you can use all the available options to print the document.