Form 3800 Part III Line 1aa is for Employee retention (Form 5884-A). The IRS has only released a Draft Form 5884-A and not the final form - <a rel="nofollow" target="_blank" href="
https://www.irs.gov/pub/irs-dft/f5884a--dft.pdf">https://www.irs.gov/pub/irs-dft/f5884a--dft.pdf</a>
Once the IRS releases the final 5884-A it can be completed and filed with the tax return. The tax return will have to be printed and mailed with the Form 5884-A attached.
