Many active traders end each year flat with no positions open and being carried from one year to the next. While this can make things easier, it is also common for even an active trader to sometimes carry over trades. If you have open positions and grab the transactions that occurred in the calendar year from your brokerage, unless you give the matching program the data on the open positions, the trades would not be matched correctly.
Therefore, you must go back and capture the information which the matching program needs for the open positions. Precisely how you will determine whether you had open positions is going to vary from brokerage to brokerage. For instance, the download for Datek style accounts at Ameritrade identifies "baseline positions." These are positions that were open on January 1st of the year.
If you believe you had open positions but cannot determine how to tell, call your brokerage to help you find out. Of course this years TradeMatcher output will have the information for next year. Once you have identified the open positions, then you need to work backwards through last year's history (i.e. starting at the end of December and moving earlier in the year) until you find the opening of each such trade position. Then for each trade you need to capture the five pieces of data identified in Appendix B.
Ultimately, you want to capture the data to the NotePad such that it looks like this:
Note several characteristics of this data: It is chronological. The purchases have negative values representing flow of funds out of the account and vice versa. Finally, in this example the words BUY and SELL are used. In your case, you would use BUY and SELL if that is the choice used in the rest of your data downloaded from your brokerage.
Once you have this data in hand, you will essentially use the TradeMatcher in two passes. You will apply the supplied script up to the match command, but you will delete the match command in the script and any commands thereafter, such that your project folder contains a file that is preprocessed to the five essential data pieces, but not matched.
You will then copy and paste your collected carryover data to the top of that file (using NotePad). Review the file carefully for uniformity. Lack of care here can of course cause erroneous results! If the data you add matches the format of the preprocessed portion, save the amended file.
Now you simply edit the script file to contain the single line to match the data and run the TradeMatcher with that script.
In summary, you collect the data for the carryover positions and run the TradeMatcher to preprocess the brokerage file where it is ready to be matched. You then paste in the carryover data at the top of the file and review to make sure all looks well. Finally, you run the TradeMatcher again with the script edited to match only (or to match and to wash if you are applying the wash filter).