The $600 stimulus payments from the latest $900 billion coronavirus relief act are hitting bank accounts and mailboxes for millions of Americans.

And for about 8 million Americans, the money will be sent on a debit card, which the IRS and U.S. Treasury Department started sending out this week, according to a statement.

The Treasury Department and IRS are sending some of the payments on debit cards to speed the delivery, according to the agency. It also said that the format of payment may be different from the first round, meaning that even if you didn't get a card the first time, you might now.

Previously, the cards, sent in May and June, were issued by MetaBank N.A. and came in a plain envelope from Money Network Cardholder Services. There was no indication on the envelope that the correspondence was coming from the IRS or Treasury.  Recipients, expecting a direct deposit payment or paper check, thought the debit card was a scam and may have thrown it away, Treasury officials said.

If you get the second stimulus payment on a debit card, here are some things to look out for.

The card will come in a marked envelope

The debit cards loaded with stimulus payments will be delivered in white envelopes that prominently display the U.S. Treasury Department seal, according to a statement from the department.

Like the first round, the payments will be sent on a Visa debit card and will also have the issuing bank name, MetaBank N.A. on the back of the card. Mailed with each card will be instructions on secure activation and use, according to the Treasury.

You can use the debit card like any other

Economic impact payments sent in plastic form will have to be activated like any other debit or credit card by calling customer service and setting a pin. People will also be able to hear their total balance when they activate their cards.

The debit card can be used anywhere debit cards are accepted, including in person, online or over the phone. That means that people can use the card for shopping or to pay rent, utilities or other bills.

You can also withdraw cash from the debit card for free at an in-network ATM or transfer the funds to a bank account without fees as was the case with the first round of cards.

The funds don't expire, but the card will

The debit cards have validity dates embossed on them, but that doesn't apply to the funds, which will not expire.

If you still have money on the card when it is no longer valid, you must call customer service to request your funds in the form of a check, according to the cardholder agreement.

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There are still some costs with the card

There are some some costs associated with using the debit card, which are laid out in the fee schedule.

The first withdrawal fee from an out-of-network ATM is waived but all others are subject to a charge. There are also fees associated with making a balance inquiry at an ATM and making a bank teller over-the-counter cash withdrawal more than once.

Fees also apply if you're using the card outside the U.S. Unlike the previous cards, there is no charge to reissue a card that has been lost or stolen.

To avoid any fees, make sure you know what ATMs are in-network, so you can withdraw money without a charge. And, if you need to check your balance, you can do so for free through the online portal at eipcard.com or by calling customer service.

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CHECK OUT: Suze Orman: Don't pay off debt with a second stimulus check — here's your 'first priority' via Grow with Acorns+CNBC.

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