What happens if I contribute to a SIMPLE IRA after I've already filed US taxes for that year?

Question

I've already submitted my US tax return and received my refund for the 2019 tax year. However I just learned that the IRA contribution deadline was pushed back along with the tax deadline.

Due to some confusion, I didn't make any SIMPLE IRA contribution for 2019, but now would like to get one in before the new deadline.

Will my contribution mean that I have paid too much in taxes for 2019 and will get an extra refund next year? Or should I submit an amended 2019 return after the IRA contribution? What is the best way of going about this?

UPDATE: Looks like the SIMPLE IRA deadline for employee contributions might actually have been 12/31, not tax day. But I'm getting mixed information from the Internet.

Answer 1

SIMPLE employee contributions must come out of wages paid during the tax year, though employer has 30 days to deposit it, thus Jan. 30 for Dec. payroll. See https://www.irs.gov/retirement-plans/simple-ira-plan-faqs-contributions . If self-employed you could retroactively declare yourself paid in Dec. up to Jan. 30; OTOH self-employed with no eligible employees could do SEP instead, up to filing deadline for the business return (which for sole prop or disregarded LLC is your individual return).

Or since you didn't contribute to the SIMPLE (and assuming there is no other relevant plan you left out of your Q) you can set up and contribute deductibly to a 'plain' IRA up to the extended filing deadline (July 15), but max $6000 ($7000 if old).

If you are self-employed, or otherwise have influence with the owners, you might want to look at all of publication 560 which covers multiple options. (Also available in PDF, which I prefer; use the link at the top of the page for "Publications", or just truncate the URL.)