Note 7 - Income Taxes (Tables)

12 Months Ended

Mar. 31, 2018

Notes Tables

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

	Year Ended March 31
	2018		2017			2016
Current taxes
Federal	$	5,899,574	$	6,034,924		$	5,754,428
State		160,670		138,689			186,822
Deferred taxes
Federal		31,800		(25,196	)		(55,254	)
State		4,108		(1,275	)		(1,214	)
Income tax provision	$	6,096,152	$	6,147,142		$	5,884,782

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

	Year Ended March 31
	2018			2017			2016
Tax expense at U.S. statutory rate	$	6,282,771		$	6,645,733		$	6,272,341
State income taxes, net of Federal benefit		103,240			83,116			118,057
Domestic manufacturing deduction		(495,361	)		(536,063	)		(476,932	)
Municipal interest		(1,378	)		(4,207	)		(4,171	)
Tax Reform Act effect on deferred tax assets		206,693			-			-
Other		187			(41,437	)		(24,513	)
Income tax provision	$	6,096,152		$	6,147,142		$	5,884,782

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

	March 31
	2018		2017
Paid time off accrual	$	59,171	$	109,298
Inventory reserve		41,572		81,743
Depreciation and amortization		81,385		52,378
Stock-based compensation deductions		55,886		86,335
Unrealized loss on marketable securities		273,360		21,852
Other		61,281		5,449
Deferred tax assets	$	572,655	$	357,055