Given that Azure and AWS now have/will have regions certified for National Security (AKA classified) workloads, absolutely. (Disclaimer- I work for a major clou

Given that Azure and AWS now have/will have regions certified for National Security (AKA classified) workloads, absolutely. (Disclaimer- I work for a major cloud service provider). But when trying to replace a super high profile, monolithic, contentious government system like this your problems are going to be much deeper than what infrastructure/platform to pick. This is project where, fundamentally, a large part of the organizations board (in other words the further right wing representatives in congress) are basically opposed the entire mission of tax collection. The tax code (which is basically the requirements doc) is 16,845 pages long (although I don't know how much of that is individual income tax related). That's before for all the analytics, reporting, interfaces, and other add on's that the design committees take on. I can almost assure you that's the MASSIVE requirements tome they dev team is dealing with. They'll probably try to break things up and do things in an agile way. They may even have all the trappings of Scrum up to a Scrum of Scrums organization, but my guess is that the executive teams in charge are going to have a hard time coping with anything besides good old waterfall style implementation and can't fathom releasing the system in small parts (and with the ancient monolith in place it may be very difficult to so anyways.) On top of all that, this system WILL be the subject of multiple lawsuits, even if it behaves exactly the same as the old system- people love suing about their tax bill. This causes all sorts of hand wringing and worry from the executive team, seemingly crazy refusal to change away "from the way we've always done it", and countless review meetings. Finally the very existence of the IRS is treated with distaste by large number of members of congress, who will drag any flaws in the system up in front of committee and pillory everyone involved. Given the project context, it'll be a real achievement to get it updated at all. So long as they are able to break up the monolith, it doesn't really matter what it targets at the start, at least there becomes a hope it can get moved later.