Note that IRS will mail you notices and/or a check to the most recent address that it has on file for you. Of note:
Nowadays IRS is very slow to pay refunds to Canadians and other non-residents making refund claims based on 1042-S slips. read See https://taxpayeradvocate.irs.gov/Media/Default/Documents/2017-ARC/ARC17_Volume1_MSP_15_International.pdf
Keep these links in mind should you not receive the refund due to the address change https://www.irs.gov/individuals/understanding-your-cp32a-notice Form 3911, Taxpayer Statement Regarding Refund. I suggest checking with IRS (telephone no on my website homepage) periodically to see that they’ve processed your return and refund check. You can also try https://sa.www4.irs.gov/irfof/lang/en/irfofgetstatus.jsp or https://www.irs.gov/newsroom/irs2goapp
Below are other ways you can change your address with IRS before and after tax return filing
Use Form 8822, Change of Address or Form 8822-B, Change of Address or Responsible Party - Business
Tax return- Use your new address when you file
Written statement - Send IRS a signed written statement with your:
full name
old address
new address
social security number, ITIN, or EIN
Mail your signed statement to the address where you filed your last return.
Oral notification -Tell IRS in person or by telephone. IRS will need you to verify your identity and the address it has on file for you. Please have ready:
your full name
your address
your date of birth
your social security number, ITIN or EIN
If you filed a joint return, and are still residing with your spouse, both you and your spouse should sign the form or statement.If you filed a joint return and you now have separate addresses, each of you should notify us of your new, separate address.
Authorized representatives filing a form or written statement to change an address for a taxpayer must attach a copy of their power of attorney or Form 2848, Power of Attorney and Declaration of Representative. Unauthorized third parties can't change a taxpayer's address.
Changes of address through the U.S. Postal Service (USPS) may update your address of record on file with IRS based on what they retain in their National Change of Address (NCOA) database. However, even when you notify the USPS, not all post offices forward government checks, so you should still notify IRS.
For changes of address relating to an employment tax return, IRS issues confirmation notices (Notices 148A and 148B) for the change to both the new and former address.
It can take four to six weeks for a change of address request to fully process.