Note 7 - Income Taxes (Tables)

12 Months Ended

Mar. 31, 2017

Notes Tables

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

	Year Ended March 31
	2017			2016			2015
Current taxes
Federal	$	6,034,924		$	5,754,428		$	6,608,923
State		138,689			186,822			330,971
Deferred taxes
Federal		(25,196	)		(55,254	)		125,070
State		(1,275	)		(1,214	)		6,356
Income tax provision	$	6,147,142		$	5,884,782		$	7,071,320

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	Year Ended March 31
	2017			2016			2015
Tax expense at U.S. statutory rate	$	6,645,733		$	6,272,341		$	7,503,886
State income taxes, net of Federal benefit		83,116			118,057			216,518
Domestic manufacturing deduction		(536,063	)		(476,932	)		(600,207	)
Municipal interest		(4,207	)		(4,171	)		(11,489	)
Other		(41,437	)		(24,513	)		(37,388	)
Income tax provision	$	6,147,142		$	5,884,782		$	7,071,320

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	March 31
	2017		2016
Vacation accrual	$	109,298	$	118,611
Inventory reserve		81,743		90,825
Depreciation and amortization		52,378		(30,174	)
Stock-based compensation deductions		86,335		115,257
Unrealized loss (gain) on marketable securities		21,852		(257,545	)
Other		5,449		14,214
Long-term deferred tax assets	$	357,055	$	51,188