	June 30,
	2021			2020
Restricted cash and other receivables	$	1,208,598		$	586,893
Restricted cash equivalents		86,322			433,709
Corporate bonds		516,350			493,879
Certificates of deposit		326,927			85,953
Municipal bonds		42,957			—
Asset backed securities		25,085			—
U.S. treasury securities		3,009			48,952
Total funds held for customers		2,209,248			1,649,386
Less - income earned by the Company included in other current assets		(650	)		(5,136	)
Total funds held for customers, net of income earned by the Company	$	2,208,598		$	1,644,250

Income earned by the Company that is included in other current assets represents interest income, accretion of discount (offset by amortization of premium), and net unrealized gains on customer funds that were invested in money market funds and short-term marketable debt securities. Earnings from these investments are contractually earned by the Company and are expected to be transferred into the Company’s corporate deposit account upon sale or settlement of the associated investment.

Below is a summary of the fair value of funds held for customers that were invested in short-term marketable debt securities (in thousands):

	June 30, 2021
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Corporate bonds	$	516,364	$	24	$	(38	)	$	516,350
Certificates of deposit		326,927		—		—			326,927
Municipal bonds		42,952		5		—			42,957
Asset backed securities		25,081		4		—			25,085
U.S. treasury securities		3,010		—		(1	)		3,009
Total	$	914,334	$	33	$	(39	)	$	914,328

	June 30, 2020
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Corporate bonds	$	491,950	$	1,936	$	(7	)	$	493,879
Certificates of deposit		85,841		115		(3	)		85,953
U.S. treasury securities		48,949		4		(1	)		48,952
Total	$	626,740	$	2,055	$	(11	)	$	628,784

The amortized cost and estimated fair value amounts include accrued interest receivable of $1.9 million and $2.9 million at June 30, 2021 and 2020, respectively. See Note 4 for additional information about the fair value measurement of short-term investments.

As of June 30, 2021, approximately 97%, or $882.4 million, of the total funds held for customers invested in marketable debt securities mature within one year and approximately 3% or $31.9 million mature thereafter. As of June 30, 2020, 100% of the funds held for customers invested in short-term marketable debt securities matured within one year.

As of June 30, 2021, approximately 60 of the more than 260 investment positions were in an unrealized loss position. The following tables present the gross unrealized losses and fair values of those investments that were in an unrealized loss position as of the periods presented (in thousands):

	June 30, 2021
	Fair value		Unrealized losses
Corporate bonds	$	79,359	$	(38	)
U.S. treasury securities		2,501		(1	)
Total	$	81,860	$	(39	)

	June 30, 2020
	Fair value		Unrealized losses
Corporate bonds	$	31,785	$	(7	)
Certificates of deposit		20,006		(3	)
U.S. treasury securities		14,990		(1	)
Total	$	66,781	$	(11	)

Investments with unrealized losses have been in a continuous unrealized loss position for less than 12 months. The Company does not intend to sell the investments and it is not likely that the Company will be required to sell the investments before recovery of their amortized cost bases, which may be at maturity. Therefore, the Company does not consider those unrealized investment losses as other-than-temporary impairment of the investments. There have been no significant realized gains or losses on the short-term investments during the years ended June 30, 2021, 2020 and 2019.

The Company has not recorded an allowance for credit losses on investments that were in an unrealized loss position as of June 30, 2021 because they were not significant.