	As of March 31, 2021			As of December 31, 2020
Revolving credit facility(A)	$	179,179		$	165,407
Term loan		200,000			200,000
British pound sterling term loan(B)		964,810			956,900
Australian term loan facility(B)		911,760			923,280
4.000% Senior Unsecured Notes due 2022(B)		586,500			610,800
2.550% Senior Unsecured Notes due 2023(B)		551,320			546,800
3.325% Senior Unsecured Notes due 2025(B)		586,500			610,800
2.500% Senior Unsecured Notes due 2026(B)		689,150			—
5.250% Senior Unsecured Notes due 2026		500,000			500,000
5.000% Senior Unsecured Notes due 2027		1,400,000			1,400,000
3.692% Senior Unsecured Notes due 2028(B)		826,980			820,200
4.625% Senior Unsecured Notes due 2029		900,000			900,000
3.375% Senior Unsecured Notes due 2030(B)		482,405			—
3.500% Senior Unsecured Notes due 2031		1,300,000			1,300,000
	$	10,078,604		$	8,934,187
Debt issue costs and discount, net		(79,066	)		(68,729	)
	$	9,999,538		$	8,865,458

As of March 31, 2021, principal payments due on our debt (which exclude the effects of any discounts, premiums, or debt issue costs recorded) are as follows (amounts in thousands):

2021	$	—
2022		586,500
2023		551,320
2024		1,090,939
2025		1,551,310
Thereafter		6,298,535
Total	$	10,078,604

As previously discussed in Note 3, we entered into a $900 million interim credit facility on January 15, 2021, of which we borrowed £500 million. We paid off and terminated this facility on March 26, 2021.

On January 15, 2021, we amended our unsecured credit facility (“Credit Facility”). The amendment extended the maturity of our $1.3 billion revolving facility to February 1, 2024 and can be extended for an additional 12 months at our option. The maturity date of our $200 million unsecured term loan facility was extended to February 1, 2026.

In addition to extending the maturity date, the amendment improved interest rate pricing for both facilities. Under the amended Credit Facility and at our election, loans may be made as either ABR Loans or Eurocurrency Loans. The applicable margin for term loans that are ABR Loans is adjustable on a sliding scale from 0.00% to 0.85% based on our current credit rating. The applicable margin for term loans that are Eurocurrency Loans is adjustable on a sliding scale from 0.85% to 1.85% based on our current credit rating. The applicable margin for revolving loans that are ABR Loans is adjustable on a sliding scale from 0.00% to 0.55% based on our current credit rating. The applicable margin for revolving loans that are Eurocurrency Loans is adjustable on a sliding scale from 0.825% to 1.55% based on our current credit rating. The amended Credit Facility retained the facility fee that is adjustable on a sliding scale from 0.125% to 0.30% based on our current credit rating and is payable on the revolving loan facility.

On March 24, 2021, we completed an £850 million senior unsecured notes offering in two tranches. See below for details of each tranche:

On March 24, 2021, we completed a £500 million senior unsecured notes offering. The notes were issued at 99.937% of par value, and interest on the notes is payable annually on March 24 of each year, commencing on March 24, 2022. The notes pay interest in cash at a rate of 2.500% and mature on March 24, 2026.

On March 24, 2021, we completed a £350 million senior unsecured notes offering. The notes were issued at 99.448% of par value, and interest on the notes is payable annually on April 24 of each year, commencing on April 24, 2022. The notes pay interest in cash at a rate of 3.375% and mature on April 24, 2030.

We used proceeds from the £850 million senior unsecured notes offering to payoff the interim credit facility and reduce our revolving facility by £341 million on March 26, 2021.

On January 6, 2020, we entered into a £700 million unsecured sterling-denominated term loan with Bank of America, N.A., as administrative agent, and several lenders from time-to-time are parties thereto. The term loan matures on January 15, 2025. The applicable margin under the term loan is adjustable based on a pricing grid from 0.85% to 1.65% dependent on our current credit rating. On March 4, 2020, we entered into an interest rate swap transaction (effective March 6, 2020) to fix the interest rate to approximately 0.70% for the duration of the loan. The current applicable margin for the pricing grid (which can vary based on our credit rating) is 1.25% for an all-in fixed rate of 1.95%.

With the amendment of our Credit Facility and the termination of our $900 million interim credit facility, we incurred approximately $2.3 million of debt refinancing costs in the first quarter of 2021.

Our debt facilities impose certain restrictions on us, including restrictions on our ability to: incur debts; create or incur liens; provide guarantees in respect of obligations of any other entity; make redemptions and repurchases of our capital stock; prepay, redeem, or repurchase debt; engage in mergers or consolidations; enter into affiliated transactions; dispose of real estate or other assets; and change our business. In addition, the credit agreements governing our Credit Facility limit the amount of dividends we can pay as a percentage of normalized adjusted funds from operations (“NAFFO”), as defined in the agreements, on a rolling four quarter basis. At March 31, 2021, the dividend restriction was 95% of NAFFO. The indentures governing our senior unsecured notes also limit the amount of dividends we can pay based on the sum of 95% of NAFFO, proceeds of equity issuances, and certain other net cash proceeds. Finally, our senior unsecured notes require us to maintain total unencumbered assets (as defined in the related indenture) of not less than 150% of our unsecured indebtedness.

In addition to these restrictions, the Credit Facility contains customary financial and operating covenants, including covenants relating to our total leverage ratio, fixed charge coverage ratio, secured leverage ratio, consolidated adjusted net worth, unsecured leverage ratio, and unsecured interest coverage ratio. The Credit Facility also contains customary events of default, including among others, nonpayment of principal or interest, material inaccuracy of representations, and failure to comply with our covenants. If an event of default occurs and is continuing under the Credit Facility, the entire outstanding balance may become immediately due and payable. At March 31, 2021, we were in compliance with all such financial and operating covenants.