If you believe your original ITR was correct, do not pay the demand immediately. Instead, analyze the specific "adjustment" mentioned in the Section 143(1) intimation. If the discrepancy is due to a system error or data mismatch (like missing TDS credit), file an online Rectification Request through the Income Tax e-Filing portal. If you identify a genuine mistake in your original filing, you may need to file a revised return or pay the tax demand.