If the IRS is still processing your return, they may need additional information from you. However, it is still possible they will use the return information to process your stimulus payment. If you have not filed for 2018 or 2019, you may have to claim a credit on your 2020 taxes to get the stimulus payment. Review some of the information in the links below.
Per the IRS:
If you did not receive the full amount to which you believe you are entitled, you will be able to claim the additional amount when you file your 2020 tax return. This is particularly important for individuals who may be entitled to the additional $500 per qualifying child dependent payments. For VA and SSI recipients who don’t have a filing requirement and have a child, they need to use the Non-Filer tool (link) on IRS.gov by May 5 in order to have the $500 added automatically to their $1,200 Economic Impact payment. We encourage people to review our “How do I calculate my EIP Payment” question and answer (See question 11).