You can postpone filing your tax return, HOWEVER you would need to file an extension request along with the estimated taxes due. The extension only gives you additional time to file your return, not additional time to pay your taxes.
If you are unable to pay your taxes in full, you can request a payment plan from the IRS. There are multiple options available. To learn more about an IRS installment payment plan click https://www.irs.gov/payments/payment-plans-installment-agreements#q02