The terminal digit filing system (TDFS)
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What is the Terminal Digit Filing System (TDFS) in the Navy?

The Navy Medical Department uses the Terminal Digit Filing System (TDFS) to file records. these records are filed according to the last two numbers of the member’s social security number (SSN). They also use color-coding of the record jacket and using block filing systems as well.

Understanding how the TDFS filing system works

Let’s understand how the TDFS filing system works.

The nine-digit social security number is divided into three groups. The TDFS system changes the direction in which social security numbers are read.

Take, for example, SSN 123-45-6789. The TDFS system reads it like this:

Primary NumberSecondary NumberThird Number
8967123-45
How SSNs are rearranged in TDFS

On the record jacket, the family member prefix (FMP) is also added to the patient’s social security number showing a beneficiary’s relationship to the sponsor.

For example, the FMP for active duty Personnel is while the FMP for a spouse is 30.

Under the TDFS, the Central files are divided into 100 equals sections. and each section is identified by a maximum of 100 file guides bearing the 100 primary numbers, 00 consecutively running up to 99.

Each of these 100 sections contains records whose last two digits correspond to the section’s primary number. You could see for example that if someone had a social security number ending in 56, then that would be the way their file is sorted into, section 56.

How secondary numbers work in TDFS

Also, within each of these 100 sections, records are filed in numerical sequence according to their secondary numbers. And as you can see the secondary numbers are the two numbers that are immediate to the left of the primary numbers.

Color-coding was introduced to TDFS to make it easier

Color coding was introduced to make filing the records easier. The second to last digit of the social security number is pre-printed on the record jacket. And the color of the record jacket corresponds to the pre-printed digit. Take a look at the table below to see the corresponding colors.

Record Color StockForm Number
OrangeNAVMED 6150/20
GreenNAVMED 6150/21
YellowNAVMED 6150/22
GreyNAVMED 6150/23
TanNAVMED 6150/24
BlueNAVMED 6150/25
WhiteNAVMED 6150/26
AlmondNAVMED 6150/27
PinkNAVMED 6150/28
RedNAVMED 6150/29
Record color-coding

There are centralized files that have records based upon more than 200 SSNs or file of more than 200 records.

When this is the case you may need to use the tertiary or third number system in the filing.

How is the TDFS filing system is almost full proof

In a properly maintained terminal digit, color-coded and block filing system, it is almost impossible to misfile a record.

If you do happen to misfile a record, the left digit of the file’s primary number will attract attention because of the color difference.

If someone so happens to miss bile the record with the wrong right primary number, this may cause a break in the diagonal pattern formed by the blocking within the color group. Again this would stick out like a sore thumb.