Short answers about Lou and US filing from Canada. For the tax details, see the guides.
About Lou
What does Lou do?
You upload the Canadian tax return you already filed (or your slips). Lou reads it on your own device, converts everything to US dollars, works out your US return, and fills the official IRS forms. Every number shows which Canadian box it came from and which rule moved it.
Who is Lou for?
US citizens, dual citizens and green card holders who lived in Canada for the whole tax year. Lou isn't built for people who moved between the countries during the year (a dual-status return), Canadians with no US status who need a nonresident return, or snowbirds filing Form 8840. Lou also doesn't do Quebec returns yet (see below).
Does Lou work if I live in Quebec?
Not yet. Quebec has its own return, its own slips (such as the Relevé 1) and its own rules that affect the foreign tax credit, and Lou hasn't been checked against them, so it stops instead of guessing. If you lived in Quebec on December 31 of the tax year, ask a cross-border tax professional. Lou works for every other province and territory.
Which tax years does Lou cover?
2023, 2024 and 2025, plus FBAR worksheets for the six years that apply (2020 to 2025 after October 15, 2026). Tax year 2026 will be added before the 2027 filing season.
What do I need to get started?
Your Canadian T1 return as a PDF from your tax software or CRA My Account, and Social Security numbers for you, your spouse and any children you claim. If you don't have the T1 PDF, your slips plus your Notice of Assessment work too. Lou asks for anything the T1 doesn't show, such as account balances or investment sales.
Which Canadian documents can Lou read?
The T1 General and Notice of Assessment, and these slips: T4, T4A, T4A(P), T4A(OAS), T4E, T4RSP, T4RIF, T5, T3, T5008 and T5007. PDFs, CSV exports and phone photos all work. Anything read from a photo that Lou isn't sure of is marked "Please check".
Which US forms does Lou prepare?
Form 1040 and Schedules 1, 1-A, 2, 3, B, C, D and 8812; Form 1116 (including the AMT version), 2555, 6251, 8833, 8938, 8949, 8621, Forms 3520 and 3520-A, and an FBAR worksheet. You also get a line-by-line guide from each Canadian box to each US line, and a review package you can hand to a professional.
Does Lou file my return?
No. Lou prepares the forms; you review, sign and file them. You can mail the return or enter the figures into e-file software. The FBAR can only be filed by you online through FinCEN's BSA E-Filing System, and Lou gives you a worksheet to copy from.
Is Lou tax advice?
No. Lou is software, not a tax preparer. It follows official IRS and CRA sources and flags situations that need judgment instead of guessing, but you are responsible for your return. See the notices.
Privacy
Where do my tax documents go?
Nowhere. Lou reads PDFs and photos, does the math and fills the forms inside your browser. There is no account, no server that receives your documents, no cloud text recognition, no AI service and no analytics. The only things that ever reach our server are the payment for a key (handled by Stripe), a request to email you a lost key, and messages you send through Report a problem. None of them includes your tax information. See the privacy policy.
How can I check that?
The app blocks connections to other websites, and you can watch its network activity in your browser's developer tools while you work. Lou's source code is public on GitHub.
What if I switch computers or clear my browser?
Your work is saved in your browser on that device. Save a backup file from Lou (you can protect it with a password) and open it on the other computer. On Chrome and Edge, Lou can also save automatically to a folder you choose.
Price
How much does Lou cost?
$49 CAD plus applicable tax, once. That covers your 2023, 2024 and 2025 returns. Each new tax year after that is $49. There's no subscription and no account.
Can I try it before paying?
Yes. Upload your documents, check the numbers and see your results for free. You pay only when you are ready to download the filled forms, the review package, the mapping guide and the FBAR worksheet.
Can I get a refund?
If Lou doesn't work for your situation, write to info@bigtimedesign.ca within 15 days of buying and you'll get a full refund, including the tax.
Can I use one key for my family?
Yes, for your own returns and the returns of family members you help. A professional preparing returns for clients needs their own key.
Filing
Will I owe US tax?
Often not. Canadian income tax is usually higher than US tax on the same income, and the foreign tax credit subtracts it from your US tax. US tax most often shows up on income Canada doesn't tax, such as TFSA earnings or Canadian funds. Some families receive a refund through the child tax credit.
Do I need to file if I won't owe anything?
Yes, if your income is over the filing threshold, which is based on your worldwide income, not on what you owe. For 2025 the threshold for a single filer under 65 is $15,750, and for married filing separately it is $5. Owing nothing doesn't remove the requirement.
When is my US return due?
April 15. If you live outside the US on that date, you automatically get until June 15 to file and pay (attach a statement saying you qualify), though interest on any tax owed runs from April 15. Form 4868, filed by June 15, extends filing to October 15. The FBAR is due April 15 with an automatic extension to October 15.
Where do I mail my return from Canada?
If you're not enclosing a payment: Department of the Treasury, Internal Revenue Service, Austin, TX 73301-0215, USA. If you are enclosing a check or money order: Internal Revenue Service, P.O. Box 1303, Charlotte, NC 28201-1303, USA. Catch-up (Streamlined) returns go to a different address; see Catching up.
My spouse is Canadian, not American. How do we file?
Usually married filing separately, with "NRA" (nonresident alien) for your spouse's number. You can instead choose to file jointly, which brings your spouse's worldwide income onto the US return and means getting them an ITIN with Form W-7. Lou supports both and tells you what each one means.
Do I need a state return?
Lou prepares the federal return only. Most Americans who have lived in Canada for years have no state filing, but some states keep treating former residents as residents while they still have ties there, such as a home, a driver's licence or voter registration. If that might be you, check with that state.
Catching up
I've never filed a US return. What now?
You're far from alone. The IRS Streamlined Foreign Offshore Procedures let you file the last three years of returns and six years of FBARs with no penalties if your failure wasn't willful. Read Catching up on missed years.
I don't have a Social Security number.
US citizens need one to file. Apply through the US Social Security Administration before you send your returns. A spouse who isn't a US person and isn't eligible for a Social Security number can use an ITIN or "NRA", depending on how you file.
Does catching up cost more?
No. The same $49 CAD key covers all three returns, 2023 to 2025, and the FBAR worksheets for the six years that apply.
Your situation
I have a TFSA, RRSP, FHSA or RESP.
Lou handles them, and each is treated differently by the US. See TFSA, RRSP and RRIF and FHSA, RESP and RDSP.
I own Canadian mutual funds or ETFs.
They are generally PFICs under US rules. Lou handles the default rules, mark-to-market and QEF elections and fills Form 8621. Read Mutual funds and ETFs first.
I'm self-employed.
Lou builds Schedule C from your T2125 figures. Under the US-Canada social security agreement you pay CPP or QPP in Canada and no US self-employment tax. See CPP, QPP and OAS.
I receive CPP or OAS.
By default Lou treats them as taxable only in Canada, the position most cross-border professionals take, and you can switch that. Read why in CPP, QPP and OAS.
I have rental property or a more complex situation.
Lou flags income it doesn't convert, such as rental income, instead of leaving it out. Consider a qualified cross-border tax professional for rental or complex business income, foreign corporations or trusts, an estate, or a move between countries. Lou's review package is designed to hand to one.
Help
I think Lou got something wrong.
Please tell us through Report a problem or at info@bigtimedesign.ca, with the tax year and what you expected. Don't send your tax documents or identification numbers; we never need them.