Demand u/s 143(1)(a)

Some income were not reported while filing return for AY 17-18 but the same were mentioned in 26As.
Demand raised in initimation was not opposed & return was not revised

Now every refund from further AYs are adjusted against outstanding demand.

Although the expense against income which was not reported will nullify the effect of excess tax demand , but unable to revise return.

As far as I understand, even rectification is not possible because I have to introduce new income in return which in my opinion is not apparent from record earlier filed.

Please guide.