In what year did the IRS first provide tax forms in Adobe PDF?

According to the article, 'PDF in Government' on the Adobe Acrobat Users website, the IRS set up its website, www.irs.gov, in 1995. The specific goal of the website was to make tax forms and information products available electronically. Their format choice was Adobe PDF (Portable Document Format). Tax forms started becoming available as fill-in PDFs in 1997. Every tax form became fill-ins by 1999.