Current tax law says the IRS cannot share tax information with other government agencies. Now the Treasury Inspector General for Tax Administration has suggested that the IRS ask Congress to change the law. This will allow the IRS to share information.
Expect something out of Congress after a while, to achieve precisely this. Turn on your legislative auto-trackers to look for amendments to 26 U.S.C. Section 6103.
What does this mean? I think it might mean that the IRS will be able to enforce Form 1040C filings, for one. I haven’t seen this done in 21 years of practicing law. (These are final tax returns filed by aliens as they leave the U.S.). It means that there will be better matching for how many days an alien was present in the U.S. (The IRS will be able to cross-reference immigration entry/exit data with tax return filings, thus making it difficult for people to stay here too long without triggering tax return filing requirements.)