If the 90 day probation period was your only gap in insurance coverage during 2016, you should not have to pay a penalty, as it would appear to fall within the guidelines for a "short gap," described below.

Tax penalties apply to each individual uninsured adult or child in a household. If a person is uninsured for only part of the year, the penalty is prorated to cover only the uninsured months. No penalty is assessed for a "short gap," an uninsured period less than three months long. You are only allowed one short gap per year.

For more detailed information, please see this TurboTax Tax Guide Affordable Care Act Decoded.