Conditional tag if=confirmation_date more than 1 year ago?

afa vzw

Hi,
I would like to keep my mailing list as current as possible, and thinking of the GDPR I was thinking it would be good to reconfirm my users after a while. I don't have double opt-in turned on, but am at the moment using a conditional "you haven't confirmed yet" window in every email if user is not confirmed.
Could I somehow make a conditional tag that reappears after 1 year of confirmation, more or less saying "are you still with us?"

afa vzw

Hi,
I've gotten a little bit further! Using this {IF} tag I seem to be able to in this case see all the people that confirmed before the GDPR started (which as a result gives me a good refresh now 1 year in)
{if:var.{subtag:confirmed_date|type:time|format:%Y%m%d}<20180525}

I noticed that the "if" tag doesn't work if the value it's referring to is a variable as well. Is that true?
eg. {if:var.{subtag:confirmed_date|type:time|formate:%Y%m%d}<var.{date:1|format:%Y%m%d|remove:31536000}} didn't work but
{if:var.{subtag:confirmed_date|type:time|format:%Y%m%d}<20180701} did