Konjunktiv I is a special verb form with no direct equivalent in many languages; its core function is to report someone else's words without the speaker taking responsibility for their truth. An ordinary reporting clause like "the minister said he has no time" does not always distinguish between neutrally relaying someone's words and personally endorsing them. Formal German — especially journalism, reports, and news — resolves this ambiguity through a distinct verb form separate from the indicative: Er sagt, er habe keine Zeit instead of er hat. The reader immediately understands this is reported speech, quoted rather than confirmed or denied. This neutrality is exactly what distinguishes the German journalistic style, and it is why Konjunktiv I is nearly absent from everyday speech yet dominant in every news bulletin and official report.
Mechanically, Konjunktiv I is built from the verb stem plus endings that stay largely constant across almost every verb: -e for ich and er/sie/es, -est for du, -en for wir and sie/Sie, -et for ihr — a regularity that even exceeds the verb sein itself, which instead has its own special forms: ich sei, du seist, er sei, all simply memorized. In other tenses, the present follows the pattern above, the past is built with the auxiliary habe or sei plus the past participle (sie habe das gesagt), and the future with werde plus the infinitive (er werde kommen) — exactly as in the indicative, but with the auxiliary itself in Konjunktiv I.
Here lies the finest point of the lesson: whenever the Konjunktiv I form happens to coincide with the ordinary indicative — as frequently happens with ich, wir, and sie/Sie (sie sagen remains sie sagen in both) — the form becomes useless because it no longer marks any distinction, so speakers switch to Konjunktiv II instead, either in its simple form where one exists (sagten) or via würde + infinitive (sie würden sagen). This substitution is mandatory whenever the forms coincide, which is exactly why ich- and wir-forms so often surface as Konjunktiv II (hätte instead of habe) rather than Konjunktiv I in actual use.
The most frequent mistake is combining dass with Konjunktiv I at once, producing Er sagt, dass er habe keine Zeit, when the standard rule requires dropping dass entirely when Konjunktiv I is used, keeping normal main-clause word order (verb in second position): Er sagt, er habe keine Zeit. To keep dass, the sentence must revert to subordinate-clause order with the verb pushed to the end: Er sagt, dass er keine Zeit habe.