Each taxpayer subject to premium tax under Insurance Article, §6-101, Annotated Code of Maryland, shall declare an estimated annual tax if the taxpayer’s total tax for the current tax year is reasonably expected to exceed $1,000. The declaration of estimated annual tax shall be: Filed with the Insurance Administration, on a form or in a manner approved by the Commissioner, on or before April 15 of the tax year; and A reasonable estimate of the expected annual tax liability for that year. The taxpayer shall pay to the Insurance Administration at least 25 percent of the estimated annual tax liability at the time the declaration of annual tax is filed, on or before April 15 of the tax year. Thereafter, the taxpayer shall file a quarterly payment report with the Insurance Administration, on a form or in a manner approved by the Commissioner, and pay to the Insurance Administration at least 25 percent of the estimated annual tax each quarter, on or before June 15, September 15, and December 15 of the tax year. A reasonable estimate of the annual tax shall be either: 100 percent of premium tax liability for the prior year as shown on the prior year's Final Report on the line stating “Premium Tax Due — Entire Calendar Year”; or 90 percent of the amount of the current year tax liability.