The electronic copies must be the PDF copies too...the .taxyyyy datafiles will be totally useless to you in ~1 years, the PDF files may last longer...but no promises as we don't know where things are headed.
USB flash drives in the bank safety deposit boxes will work....and when a new memory device shows up in a few years, you can copy the files to the new memory device to keep them current.
Paper does last better, as long as it is not in a home that burns down, or gets hit by a hurricane or flood. But even in a bank safe deposit box, a few zip-locks are a good idea (My mom's stuff was in one at a bank that was flooded...all the boxes filled up with water and sediment)
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____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
