Vendors of personal income tax software impose various limits on the number of returns you can file. However, CRA imposes a hard limit of 20 returns per computer. Why?
The seventh entry in CRA’s NETFILE FAQ answers this question. The explanation begins with “The CRA's primary interest is always to protect the taxpayer.” This gave me a chuckle. I can believe that protecting taxpayers is high on their list, but their primary interest is to suck up giant piles of money. OK, moving on.
The rest of the explanation is a little vague, but the concern seems to be identity theft. I guess an identity thief with personal information on many Canadians could cause trouble on a large scale with unauthorized use of NETFILE.
So there you have it. Anyone who wants to file more than 20 returns needs to NETFILE with multiple computers or could use EFILE which is intended for tax preparers.