Hi PaulV33,
Hope all is well on your end. Usually, self-employment earnings from a K-1 box 14 with an A means that the earnings are subject to self-employment taxes. The K-1 flows through to your personal tax return, the earnings will be shown on Part II of the Schedule E and you will have an SE Tax form. Does this answer your question?
Cheers,
Laura
Must I file this quarterly, then? If so, then what's the best way to estimate the quarterly income, what forms do I submit, and where do I submit them?
If the business entity does not make any estimated tax payments on your behalf, then you would be required to make estimated tax payments at the individual level.
You may use our Tax Calculator to estimate the amount of tax liability for those earnings: https://turbotax.intuit.com/tax-tools/calculators/taxcaster/. You may estimate this by using the prior year earnings or if the company gives you current earnings, you may use that as well.
Once you determine an estimated tax liability, you want to make your IRS estimated tax payments using the Form 1040-ES: https://www.irs.gov/pub/irs-pdf/f1040es.pdf and NJ estimated tax payments using the NJ-1040-ES: https://www.state.nj.us/treasury/taxation/pdf/current/1040esi.pdf.
Remember when you prepare your individual tax returns, you will pick up these estimated tax payments you made to offset your tax liability (in other words, you are pre-paying into your taxes to avoid underpayment penalties and underpaying your tax liability).
Hope this helps, please let us know if you have any further questions.
Cheers,
Laura