On January 20, 2016, the Department assessed the Taxpayer for gross receipts tax, penalty and interest for the CRS reporting periods between January 1, 2011 and December 31, 2012. On February 1, 2016, the Taxpayer protested the Department’s assessment. The Taxpayer began its business, providing construction services in New Mexico, in 2002. On September 26, 2011, the Department informed the Taxpayer via letter that it would have to switch from quarterly reporting to monthly reporting because its monthly income was over the allowed threshold. The Taxpayer was also required to switch from paper to electronic filing. The Taxpayer indicated that, as a result of these changes, it struggled to accurately report and pay gross receipts taxes, although it did continue to file. Through its Schedule C mismatch program with the IRS, the Department detected that significantly more business income was reported on the Taxpayer’s schedule C than was reported on CRS returns in New Mexico for the relevant period. The Taxpayer challenged the assessment of penalty and interest, mainly given what the Taxpayer believed was a lengthy delay in the Department’s assessment. The only issues at protest are the timeliness of the assessment, and the assessment of interest and penalty. Section 7-1-18 NMSA 1978 sets limits on the Department’s ability to assess, and generally the Department has three years from the end of the calendar year in which the tax was due to assess. However, if a Taxpayer underreports a tax liability by more than 25%, as was the case here, the Department has six years from the end of the calendar year in which the tax was due to issue an assessment. The assessment was timely based on this provision. As for the interest and penalty, interest is mandatory pursuant to Section 7-1-67 NMSA 1978, and pursuant to Section 7-1-69 NMSA 1978, the Taxpayer is subject to penalty due to negligence as none of the indicators of nonnegligence were present. The Taxpayer’s protest was denied.