I work for a small business which uses highly confidential infomation about our clients’ employees to run various government tests on their retirement plans.

At the beginning of the year we send an excel file containing information such as Social Security Numbers, Dates of Birth, and Dates of Hire to our clients. The client will then send the file back after adding new employees, Compensation amounts, and Contributions to the retirement plan.

What we need to do is deploy some method of securing this information to prevent it from becoming compromised. I have been looking into the possibility of a website where we can securely upload documents which our clients can update and then resubmit to the website but have not come across anything which looks legit.

Another option would be email encryption, but it would have to be very simple so that our clients would not be too confused.

Any help would be appreciated.

Thanks