As of December 31, 2023 and September 30, 2023, we had the following debt obligations:


(in thousands)	December 31, 2023			September 30, 2023
4.000% Senior notes due 2028	$	500,000		$	500,000
3.625% Senior notes due 2025		500,000			500,000
Credit facility revolver line(1)(2)		766,527			202,000
Credit facility term loan(1)(2)		500,000			500,000
Total debt		2,266,527			1,702,000
Unamortized debt issuance costs for the senior notes(3)		(5,672	)		(6,215	)
Total debt, net of issuance costs(4)	$	2,260,855		$	1,695,785

(1)

Unamortized debt issuance costs related to the credit facility were $2.3 million included in Other current assets and $7.0 million included in Other assets on the Consolidated Balance Sheet as of December 31, 2023 and $2.3 million included in Other current assets and $7.5 million included in Other assets on the Consolidated Balance Sheet as of September 30, 2023.

(2)

The stated maturity date under the credit facility on which both the revolver line and the term loan will mature and all amounts then outstanding will become due and payable is January 3, 2028. However, if our outstanding 2025 Senior Notes have not been refinanced to mature on or after April 3, 2028 or redeemed by November 16, 2024, all amounts outstanding under the credit facility will become due and payable on November 16, 2024. The term loan will begin amortizing in March 2024, with payments of $9.4 million in 2024, $21.9 million in 2025, and $25.0 million in 2026 and 2027, and $418.7 million in 2028.

(3)

Unamortized debt issuance costs for the senior notes are included in Long-term debt on the Consolidated Balance Sheets.

(4)

As of December 31, 2023 and September 30, 2023, $12.5 million and $9.4 million, respectively, of debt associated with the credit facility term loan was classified as short term with the remaining balance classified as long term.

In February 2020, we issued $500 million in aggregate principal amount of 4.0% senior, unsecured long-term debt at par value, due in 2028 (the 2028 notes) and $500 million in aggregate principal amount of 3.625% senior, unsecured long-term debt at par value, due in 2025 (the 2025 notes).

As of December 31, 2023, the total estimated fair value of the 2028 and 2025 notes was approximately $478.8 million and $491.4 million, respectively, based on quoted prices for the notes on that date.

We were in compliance with all the covenants for all our senior notes as of December 31, 2023.

Our credit facility consists of (i) a $1.25 billion revolving credit facility, (ii) a $500 million term loan credit facility, and (iii) an incremental facility pursuant to which we may incur additional term loan tranches or increase the revolving credit facility. As of December 31, 2023, unused commitments under our credit facility were $483 million and amounts available for borrowing were $470 million.

As of December 31, 2023, the fair value of our credit facility approximates its book value.

PTC and certain eligible foreign subsidiaries are eligible borrowers under the credit facility. As of the filing of this Form 10-Q, $221.5 million was borrowed by an eligible foreign subsidiary borrower.

Loans under the credit facility bear interest at variable rates. As of December 31, 2023, the annual rate for borrowings outstanding was 7.2%. A quarterly revolving commitment fee on the undrawn portion of the revolving credit facility is required, ranging from 0.175% to 0.325% per annum, based upon our total leverage ratio.

As of December 31, 2023, we were in compliance with all financial and operating covenants of the credit facility.

In the three months ended December 31, 2023 and 2022, we incurred interest expense on our debt of $35.3 million and $16.4 million, respectively. In the three months ended December 31, 2023, we paid $44.8 million of interest on our debt, of which $30.0 million was interest imputed on the $650.0 million ServiceMax deferred acquisition payment that we settled in the period. In the three months ended December 31, 2022, we paid $4.8 million of interest on our debt. The average interest rate on borrowings outstanding was approximately 5.7% and 4.2% during the three months ended December 31, 2023 and 2022, respectively.