1. Pay your federal estimated or past balance due taxes for an exceptionally low 1.85% fee. Note that payment via Paypal may be required if your card type is rejected.
2. A $6,000 estimated federal tax payment incurs a fee of about $111. However, if aiming to complete the Ink Business Unlimited spending threshold, you’ll earn 84,000 Chase points (75K signup bonus + 9K points for spending), valued at least $840 cash back or up to $1,260 towards travel if you have the Sapphire reserve card.
3. If you overpaid your taxes, you can request a refund when filing taxes.

If possible to pay tuition without fees, it’s a no-brainer. Even with fees, it can make sense if you won’t hit the spend threshold otherwise.

Some companies allow prepayment on a credit card with flat fees, providing an excellent way to earn miles and meet a spend threshold.

Enroll in Paypal to pay bills that don’t normally accept credit cards.

Use Plastiq to pay bills like rent or mortgage with a 2.9% fee. Note that Visa and AMEX can’t be used for mortgage payments.

While sending money to friends may not generate miles, marking payments as “goods” can earn miles with a fee of about 2.9%.

Instantly load funds onto your Amazon account to reach a spend threshold.

The Ink Cash card earns 5 points per dollar on various gift cards from office supply websites and stores, helping meet a spend threshold.

After negotiating for a bottom-line price, inquire if you can put a few thousand dollars on your card without additional fees.

Donate to your favorite organization through Paypal giving fund; you won’t have any processing fees and earn bonus points for meeting the spend threshold.

Purchase Mastercard or Visa gift cards from office supply stores to earn 5 points per dollar and donate those to charity, earning an additional 5 points per dollar spent on top of the signup bonus.

While not a method I endorse, one could prepay their credit card bill as a last resort, but be cautious of potential ramifications.