I’ve never seen the penalty imposed, and I was always taught (by ex IRS agents) to mail each return year in a separate envelope. I mailed out 15 years in separate envelopes for a client because I just loooovvee and fully support our wonderful US Postal Service (sarcasm implied) for a single client; never received one penalty letter. Howard’s idea isn’t a bad one, but I know IRS agents can be lazy (sorry IRS, but it’s true), see one 8606 and literally toss the others in the Fahrenheit 451 pile.
Honestly, I think just because the IRS can, doesn’t always mean they will, but what a layup for them. Cha Ching, how many $50 bills they could be racking up here and they don’t; strange indeed.
Go with your gut all the time MI, if mailing separately gives you the warm and fuzzies, and honestly, we are trying to insulate the client from IRS harm, go for it. You’d be in compliance and serving the client well. 50 cents per envelope won’t send them to the soup kitchen, I’m sure. Happy Thanksgiving!