New York Consolidated Laws, Tax Law - TAX § 1242. Limitations on assessment

(a) Cities over one million.  Except in the case of a wilfully false or fraudulent return with intent to evade the tax, no assessment of additional tax shall be made with respect to the taxes imposed under the authority of section twelve hundred one, after the expiration of more than three years from the date of the filing of a return, provided, however, that where no return has been filed, or where the taxpayer fails to file a report in respect of a change or correction in the amount of sales and compensating use tax liability relating to the purchase or use of items for which a sales or compensating use tax credit against the tax was claimed, as provided by law, the tax may be assessed at any time.  Notwithstanding the prior sentence, no assessment of additional tax shall be made with respect to taxes imposed under local laws enacted prior to July first, nineteen hundred thirty-eight, except in the case of a wilfully false or fraudulent return with intent to evade the tax.  Where the taxpayer files a report in respect of a change or correction in sales and compensating use tax liability, as provided by law, an assessment may be made at any time within two years after such report was filed.

(b) Cities under one million, counties and school districts.  Except in the case of a wilfully false or fraudulent return with intent to evade the tax, no assessment of additional tax shall be made with respect to taxes imposed under the authority of sections twelve hundred two through twelve hundred four, after the expiration of more than three years from the date of the filing of a return, provided, however, that where no return has been filed as provided by local law, ordinance or resolution, the tax may be assessed at any time.