More time than 6 months.

[Sqaiser]

We have applied ILR for our Tier 1 general category. Its been four months now and we received a letter from the home office saying it can take more than 6 months in our case as they are waiting for a reply from another government agency.
Also we have declared our tax but have not payed it all and are trying to get installments on it. Could it be the reason or not?

[Casa]

Very likely that HMRC are the Government department referred to.

Search the forum and you will find numerous posts about refusals due to Tier-1 tax discrepancies.

[Abc499]

Also we have declared our tax but have not payed it all and are trying to get installments on it. Could it be the reason or not?

when did you declare/submit it? if not on the time when due and declared just before/around ILR application then highly likely this could be the reason. Installment payment with HMRC should not be any issue on this case.

[Sqaiser]

It was declared ages before we applied. But we only started to pay it after applying our visas as I couldn't pay it altogether and wated to get instalments first.