https://www.irs.gov/pub/irs-pdf/i5329.pdf
Prior tax years. If you are filing Form 5329 for a prior year, you must use the prior year's version of the form. If you don’t have any other changes and haven’t previously filed a federal income tax return for the prior year, file the prior year's version of Form 5329 by itself (discussed earlier). If you have other changes, file Form 5329 for the prior year with Form 1040-X, Amended U.S. Individual Income Tax Return.
2018 Form 5329 - https://www.irs.gov/pub/irs-prior/f5329--2018.pdf
2019 Form 5329 - https://www.irs.gov/pub/irs-prior/f5329--2019.pdf
