My understanding is that , your employer will send this information just like W-2 to IRS if you have insurance or not through them.

If you are self employed, and have insurance through third party markets, they are reported accordingly to IRS.

If IRS have no information about your insurance then that might be flag for them to audit you.

Remember, now a day ( after Obama CARE), we receive another form 1095 -A/B/C for tax purpose from your employer or insurance providers that clearly tells what months you had insurance.

We (file jointly) were audited once for submitting college credits and our college didn't reported to IRS our 1098-T. The college said that they made changes and didn't report to IRS if student didn't have SSN (one of us only had ITIN). Our case was closed once we send them - transkripts, amount paid to college through our bank statements and college statements and also all book costs with itemized deskriptions. It was big hassle.

Last year 2017, we had some gaps too because of employment changes But I am planning to report IRS. I don't think it is worth it. Fines increases every year for not having insurance. But if this is 1st year with some months gaps, the fine is not going to be big.
hope this helps.
IRS have the most power to get their money that you owe.