Hi, I have a small online business mainly selling on amazon, ebay, and my own website. Just received a letter from IRS saying for year 2015 returns, they have adjusted the total reported income and now I owe $2.4k in tax return, plus some interests(not much, around $100). I just checked the tax form for that year(filed early 2016), and found I did miss out one of the platform I was selling on so that total sales (of about $16k in total) was not included in the tax form.

My question is:

1. What's the consequence if I don't pay this $2.4k. This might not be much to most small businesses but the business has been terrible since 2014 for me and $2.4k is quite significant to me. From what I understand, if i don't pay the interests and penalties will keep piling up. My question is will IRS take action to collect on my business bank account for such a small amount?

2. Is there any way to negotiate it down a bit so that I pay a certain percentage of that amount to settle it with IRS?

3. Will this likely to trigger an audit? I mean I'm not hiding anything but if there's an audit I have to gather all the receipts and paperwork which could be very burdensome.

I've tried to contact my accountant and they said an interview with them cost $200 and it's probably cheaper to just pay IRS that $2.4k.